JOHN  ALEXANDER  JAMESON,  JR. 
1903-1934 


.NGINEERING  LIBRARY 


THIS  BOOK  belonged  to  John  Alexander  Jameson,  Jr.,  A.B.,  Wil- 
liams, 1925;  B.S.,  Massachusetts  Institute  of  Technology,  1928; 
M.S.,  California,  1933.  He  was  a  member  of  Phi  Beta  Kappa,  Tau 
Beta  Pi,  the  American  Society  of  Civil  Engineers,  and  the  Sigma 
Phi  Fraternity.  His  untimely  death  cut  short  a  promising  career. 
He  was  engaged,  as  Research  Assistant  in  Mechanical  Engineering, 
upon  the  design  and  construction  of  the  U.  S.  Tidal  Model  Labora- 
tory of  the  University  of  California. 

His  genial  nature  and  unostentatious  effectiveness  were  founded 
on  integrity,  loyalty,  and  devotion.  These  qualities,  recognized  by 
everyone,  make  his  life  a  continuing  beneficence.  Memory  of  him 
will  not  fail  among  those  who  knew  him. 


<6 


GILBERT 
SIGNAL  ENGINEERING 

Complete  and  thorough  instructions 
in  all  forms  of  Signaling 

FOR  BOYS 

BY 

LEE  CONOVER 

Formerly  with  Signal  Corps  U.  S.  Navy 
Prepared  under  the  Direction  of 

A.  C.  GILBERT 

Yale  University,  1909 


THE  A.  C.  GILBERT  COMPANY 

NEW  HAVEN,  CONN. 

New  York       Chicago       San  Francisco       Toronto       London 


0 


COPYRIGHT  1920 

BY  A.  C.  GILBERT 

NEW  HAVEN,  CONN. 

ENGINEERING  LIBRARY 
>/2^ 


TABLE  OF  CONTENTS 


CHAPTER 

I.     HISTORY  OF  SIGNALING 7 

II.     GENERAL  SERVICE  CODE  AND  ITS  USES        ...         14 

Wigwag  system — The  flag,  limitations  and  backgrounds — 
The  torch  and  lantern  wigwag — Wigwagging  by  searchlight. 

III.  GENERAL  INFORMATION  AND  ADVICE  TO  SIGNALISTS     .        27 

The  message — Duties  of  a  signal  unit — Interruption  of  mes- 
sages— Intervals — Code  time. 

IV.  SEMAPHORE  SYSTEM  .         .         <>         .         .         .         36 

The  semaphore  machine — Two-arm  semaphore  by  hand 
flags. 

V.     SOUND  AND  FLASH  LIGHT  SYSTEMS      ....         46 

Sound  signals  by  bugle — Signaling  by  pocket  whistle —  Flash- 
ing or  occulting  light  system  —  The  blinker  —  The  acety- 
lene lantern — Searchlight  signaling — The  heliograph — The 
Ardois  system— The  Very  system. 

VI.     TELEGRAPHY,  RADIO-TELEGRAPHY  AND  TELEPHONY   .         59 

Telegraphy — The  American  Morse  Code — Receiving  telegra- 
phy— Radio-telegraphy — Telephony — The  telephone  for  sig- 
nal purposes. 

VII.  THE  SIGNAL  TOWER 68 

Suggestions  for  erecting  a  signal  tower — Secret  codes  and 
ciphers— The  cipher  disc — How  to  make  a  cipher  outfit. 

VIII.  MARITIME  SIGNALING 77 

Flags  and  correct  way  of  using — Flags  of  the  International 
Code  and  how  used — Method  of  signaling  when  no  other 
ships  are  in  sight — Distant  signals — International  flag  waving 
system. 

IX.     U.  S.  NAVY  FLAG  SIGNALS 85 

How  navy  signals  are  executed — Calls — U.  S.  naval  flag 
etiquette— Time  for  flying  colors — Personal  flags— Yacht  flags. 

X.     MISCELLANEOUS  SIGNALS 95 

International  life  saving  signals — Signals  for  a  pilot— Inter- 
national distress  signals,  for  day — International  distress 
signals,  for  night. 

XI.     How  TO  MAKE  SIGNAL  APPARATUS  99 

How  to  make  a  field  buzzer — How  to  make  a  heliograph— How 
to  make  a  semaphore  and  blinker. 


88971 8 


FOREWORD 

To  do  big  things,  just  as  men  do  who  are  experts  in  a  certain 
kind  of  endeavor,  I  believe  is  the  greatest  wish  of  every  boy.  I 
know  when  I  was  a  boy  it  was  very  interesting  to  me  to  find  out 
all  I  could  about  electricity,  chemistry  and  other  practical  subjects 
because  they  held  my  attention.  There  was  all  kinds  of  fun  in 
this  for  me.  Whenever  I  got  working  on  my  experiments  I  had 
the  greatest  amount  of  pleasure.  Let  me  tell  you,  too,  I  was  a  happy 
boy  when  I  had  completed  my  work  and  could  show  it  to  others. 

I  remember  how  I  used  to  watch  army  men  at  signal  practice. 
It  was  mighty  fascinating  to  see  them  at  the  camp  with  their 
apparatus  and  to  observe  the  methods  they  used  to  send  messages. 
It  looked  hard,  but  when  I  thought  it  over  it  seemed  very  easy. 

Signaling  will  prove  just  as  interesting  to  you  as  it  did  to  me, 
and  because  I  think  it  means  a  great  amount  of  fun  for  you,  I 
have  had  this  book  prepared  by  a  man  who  was  an  expert  in  sig- 
nals and  who  did  very  fine  work  in  the  Navy  as  a  member  of  the 
Signal  Corps.  Every  detail  is  explained  with  the  greatest  care. 
The  facts  are  authentic  and  you  can  depend  on  this  book  to  give  you 
a  thorough  knowledge  of  signaling.  You  can  learn  about  signals 
from  the  very  beginning  when  firebrands  were  used  in  a  primi- 
tive fashion  many  years  ago  to  the  present  time  when  messages 
are  flashed  and  sent  by  the  most  modern  inventions. 


SIGNAL  ENGINEERING 


'•,•_•_••  s       j       o 

'4£IGU31, 

Competing  teams  of  the  oU>  S.  Armye  £ji$l  ^N^  on  ^the  xoof  of  the  Grand  Central 
Palace,  New  York  City,  during  a  recent  dg^a!/  cQrrt,est**  •  *  J*9 

Chapter  I 

In  Webster's  Dictionary  we  find  that  the  meaning  for  signal 
is  a  sign  and  in  looking  up  sign  find  its  definition  to  be  signal- 
ing— hence  they  are  certainly  very  closely  related.  At  any  rate 
a  signalman  is  one  who  puts  signs  into  action  and  that  is  what 
we  are  going  to  do,  By  a  little  perseverance  you  will  master 

(7) 


8 


GILBERT  BOY  ENGINEERING 


each  lesson  step  by  step  and  in  a  very  short  time,  with  the 
ease  of  a  master  signalman,  be  able  to  flash  a  message  through 
space  for  a  distance  of  twenty  miles  or  more. 

The  early  American  Indians  wrote  their  picturegraph  mes- 
sages on  the  bark  of  trees,  their  canvas  wigwams  and  other 
conspicuous  places.  The  totem  pole  of  the  Northwest  and 

Alaskan  Indians  is  a  good 
example  of  symbol  writ- 
ing. In  later  years  the 
more  advanced  tribes  de- 
vised crude  codes  by 
which  they  sent  messages 
by  means  of  smoke. 

Many  hundreds  of 
years  ago  the  ancient 
tribes  in  Europe  put  into 
practice  the  habit  of  carv- 
ing picturegraph  stories 
on  rocks.  Like  the  Ameri- 
can Indians,  they  later 
found  methods  of  sending 
their  messages  through 
Space  with  the  aid  of  a 
,  cumbersome  code  and 
lighted  torches. 

It  seems  that  the  earli- 
est forms  of  optical  teleg- 
raphy, as  visual  signaling 
is  sometimes  called,  in- 
volved the  use  of  fire- 
brands or  torches.  Of 

Boy    Scouts    in    mountain    of    N.    Y.    State    sis-       COUrSC     these     COUld     Only 

a  tree'~  be  used  at  nisht, and  his- 


GILBERT  SIGNAL  ENGINEERING 


Boys  practicing  signals  at  a  Scout  Camp. — Courtesy  of  Boy  Scouts  of  America 


Boy    Scouts^  of 
Scouts  of  America 


FIG.  4 
Denver,    Colo.,    Troop    practicing    semaphore. — Courtesy    of   Boy 


10 GILBERT  BOY  ENGINEERING 

tory  gives  us  no  reliable  records  of  any  day  signals  until  the 
earlier  forms  of  semaphore  hundreds  of  years  later. 

About  200  B.  C.  a  method  of  signaling  was  employed  by  the 
Greeks,  in  which  torches  were  used.  A  system  of  measuring 
the  flashes  or  exposures  so  as  to  make  a  simple  code  was 
invented. 

The  Romans  also  used  torches  for  signaling,  and  during  the 
early  Greek  and  Roman  Wars  probably  the  first  step  was  taken 
in  Signal  Corps  organization.  •  These  warrior  signalmen  were 
known  as  "fire  shakers,"  and  to  obtain  points  of  vantage  they 
built  in  many  places  throughout  Europe  signal  stations,  some 
of  which  are  still  standing  to  this  day. 

Mention  is  made  in  the  Old  Testament  of  lighting  signal 
fires  for  the  purpose  of  conveying  intelligence.  It  seems  that  the 
method  of  using  signal  fires  and  torches  was  very  popular  among 
the  early  signalmen.  The  fact  remains  that  even  as  late  as  the 
Civil  War  in  America  torches  were  still  in  use  by  the  Signal 
Corps  of  the  Blue  and  Gray  Armies  and  are  rivaled  today  only 
by  the  more  modern  devices  in  which  lanterns  and  electric 
lights  are  used. 

|In  the  year  1623  the  Marquis  of  Worcester  (England),  in- 
vented a  plan  of  letters  for  signaling  by  day  and  night. 

Monsieur  Amontons  (France  1663)  recommended  the  holding 
up  of  large  letters  of  the  alphabet  to  be  viewed  by  telescope. 

Robert  Hook  of  England  was  the  first  to  really  develop  the 
modern  idea  of  visual  signaling.  He  used  various  shaped  ob- 
jects, suspended  on  a  frame,  to  indicate  letters  of  the  alphabet. 

Claude  Chappe,  a  young  French  engineer,  in  1790  invented  a 
system  of  semaphore,  and  other  Frenchmen  followed  him  with 
the  more  advanced  forms  of  indicators  with  semaphoric  wings. 

During  the  reign  of  Queen  Elizabeth,  the  Duke  of  York  (later 
James  II)  introduced  a  system  of  methodized  signals  from  which 
later  sprang  the  first  British  Naval  Code. 


GILBERT  SIGNAL  ENGINEERING 


11 


FIG.    5 

Signalmen  of  the  U.   S.   Navy  on  signal  bridge  of  the  U.   S.   "Wyoming" 


12 GILBERT  BOY  ENGINEERING 

In  1816  Sir  Home  Popham  of  the  British  Navy  gave  the 
world  a  new  system  of  semaphore  telegraph,  which  was  adopted 
by  the  British  Admiralty. 

William  Penn  of  America  is  also  given  credit  for  being  among 
the  first  (if  not  the  first)  to  get  together  a  code  and  system  for 
communication  at  sea. 

In  reviewing  the  history  of  signaling  it  might  be  of  interest 
to  know  that  the  first  telescope  was  invented  about  the  year 
1600.  This  important  invention  increased  the  range  of  the 
naked  eye  to  a  very  great  extent  and  made  signaling  an  im- 
portant method  of  communication. 

The  needs  for  signaling,  we  can  see,  were  first  wanted  by 
armies  so  as  to  bring  about  rapid  exchange  of  thoughts.  It 
proved  faster  and  more  reliable  than  messengers,  who  were 
always  subject  to  delays  or  liable  to  capture.  Still,  today,  its 
paramount  use  is  found  in  the  armies  and  navies  of  the  world, 
where  the  Signal  Corps  is  without  a  doubt  the  most  important 
branch. 

In  November,  1863,  during  the  Civil  War  in  America,  when 
General  Grant  took  command  of  the  Union  Army  before  Chat- 
tanooga he  established  his  .Signal  Corps  on  a  big  mountain  and 
was  able  to  keep  in  touch  with  his  forces  during  many  of 
the  great  battles,  one  of  which  was  the  famous  "Battle  Above 
the  Clouds/'  fought  on  Lookout  Mountain.  Today  this  moun- 
tain, from  which  his  Signal  Corps  operated,  is  called  Signal 
Mountain  and  will  stand  as  an  everlasting  monument  to  the 
Signal  Corps.  If  it  is  ever  your  good  luck  to  visit  this  beautiful 
spot  in  Tennessee  you  will  then  realize  to  what  extent  accurate 
signals  were  and  can  be  exchanged. 

During  the  late  war  the  Allied  armies  used  many  ingenious 
methods  of  signaling,  including  the  improved  blinker  systems, 
sound  systems  and  radio.  One  of  the  newest  schemes  is  that  of 
sending  a  message  from  the  ground  to  aeroplanes  by  means  of 


GILBERT   SIGNAL   ENGINEERING 13 

"Panels."  This  is  done  with  a  code  and  panels  of  colored  cloth 
laid  on  the  ground. 

The  importance  of  Signal  Corps  work  can  be  realized  better 
when  it  is  known  that  the  Signal  Corps  of  the  U.  S.  Army  alone, 
during  the  time  it  took  part  in  the  war,  used  126,000  miles  of 
wire  for  intelligence  communications  by  telephone  and  telegraph 
lines.  (Liaison  work.) 

More  scientific  knowledge  of  our  neighboring  planets  will 
undoubtedly  be  accomplished  by  means  of  high  powered  signal 
apparatus.  The  matter  of  an  exchange  of  messages  with  the 
inhabitants  (if  any)  of  these  planets  is  receiving  serious  thought 
by  many  scientists.  Several  years  ago  a  plan  was  advanced  to 
do  this  by  means  of  the  heliograph  method.  This  scheme  was 
to  use  great  mirrors  with  a  huge  shutter  arrangement  so  as  to 
send  the  messages  by  means  of  great  flashes.  Who  can  tell  but 
what  you  may  be  able  to  invent  the  apparatus  to  send  a  mes- 
sage that  far?  It  would,  of  course,  take  years  to  develop,  but 
some  one  will  eventually  find  a  way  to  complete  this  wonder 
system  in  signaling. 


Chapter  II 
GENERAL  SERVICE  CODE  AND  ITS  USES 

A  code  of  signals  is  a  collection  of  symbols  agreed  upon. 
The  International  Morse  or  Continental  Code  is  the  most  widely 
used  of  all  modern  codes — due  to  its  easy  adaptability  to  so 
many  forms  of  signaling. 

The  International  Morse  Code  was  first  used  for  transmitting 
messages  by  ocean  cables  and  later  adopted  by  the  armies  and 
navies  of  the  United  States  and  Great  Britian.  By  the  official 
recognition  of  the  Army  and  Navy,  the  Boy  Scouts  and  other 
organizations  it  has  come  to  be  known  as  the  "General  Service 
Code."  From  this  point  on  in  the  book  it  will  be  called  by  that 
term. 

The  General  Service  Code  is  a  code  of  dots  and  dashes  com- 
prising the  twenty-six  letters  of  the  alphabet  and  the  numerals, 
with  additional  symbols. 

The  following  signal  systems  are  based  on  this  code: 

1.  Sound  system. 

2.  Heliograph  system. 

3.  The  Ardois  system. 

4.  Flashing  or  occulting  light  system. 

5.  Very's  night  system. 

6.  The  Wigwag  system. 

7.  Radio. 

8.  Buzzer  and  Field  Telegraph. 

The  U.  S.  Army,  commercial  telegraph  lines  and  short  cables 
at  the  present  time  use  the  American  Morse  which  has  slightly 
different  symbols. 

(14) 


GILBERT  SIGNAL  ENGINEERING 15 

Alphabet -GENERAL  SERVICE  CODE 


A 

B 

C 

D            E 

•  •• 

S0«* 

•      •»•••• 

•raao                   • 

F 

G 

H 

I           J 

K 

L 

M 

N            0 

P 

Q. 

R 

S            T 

U 

••Mi 

V 

V 

X            Y 

Z 

NUMERALS 

1    . 

»»«i«i 

«             6 

«••••• 

2    . 

>•  aaoiB»  a 

7 

__••• 

3    , 

^•4^  an  flan 

8 

•»•*««« 

4    , 

»•••  8KB 

9 

»•»«>••• 

&    • 

»•••• 

0 

~— 

CHART 


16 GILBERT  BOY   ENGINEERING 

In  using  the  General  Service  Code  with  some  of  the  systerm 
just  mentioned,  it  is  necessary  at  times  to  make  some  minor 
changes  in  the  arrangement  of  sending  numerals  and  conven- 
tional signals,  but  the  principle  of  the  code  always  remains  the 
same.  The  changes  will  be  explained  from  time  to  time  as  yoi 
become  familiar  with  the  systems. 

You  can  readily  see  the  importance  of  knowing  this  code  be 
fore  any  advance  can  be  made  in  signaling;  so  now  turn  tc 
Chart  1  where  you  will  find  the  General  Service  Code  alphabel 
and  numerals  written. 

First  study  the  alphabet.  A  good  plan  that  will  help  you  tc 
memorize  it  will  be  to  write  over  and  over  again  the  characters 
on  paper,  after  which  you  can  get  another  boy  to  test  youi 
memory  by  having  him  call  out  at  random  letters  of  the  alphabe 
to  you.  You  can  reply  in  dots  and  dashes.  Another  way  is  t 
construct  short  sentences  and  then  rewrite  them  under  the  do 
and  dash  characters.  For  example; 


N 


MUST  KNOW 


E 


The  numerals  of  the  code  are  much  easier  to  learn  than  the 
alphabet.  You  will  note  that  they  are  written  by  using  a  com- 
bination of  five  dots  and  dashes  for  each  number.  Remember 
numbers  are  always  represented  by  five  dots,  dashes,  or  a 
combination  of  both.  Number  one  is  made  with  one  dot  fol- 
lowed by  four  dashes,  .1 ;  number  two  by  adding 

L  —  1 


GILBERT  SIGNAL   ENGINEERING  17 


Condetilioml  Oittafe,  etc 


PUNCTUATION 

Period,  ••  ••  ' **  Comm&  •• 

Setnicolott  **•   «•>«  ^^GoLoti  «. 

ApOStVOphe  *mmmm*m*m* 


Of 

Quotation  Hg&Zi  (fagiatdtg  and,  en&tig)***  ++m** 


to  itutic&te  & 

r  &  Z£5#£  Zefovg  &tul  gffep  -zHovds 
to  uzulev2in&}  ********* 
Doii&le  Dct&h  (to  Ze  used  &ett£eett  pre&ttiile 

3£fa2&&3§  *    Oe£ll)C£Zl   &&t£z?€$3    cZZZsL  &Qc£y  Op  ttZgfSiS^G * 

body  stv£  <sigtia£iir>e  f  and  iozatediaiely  &epove  cpaciiott) 

mm  #••  mm 

SECONDARY   MEANINGS 

mm»mm  (II)         Mfgaiifo    Of  No 

mm.  CM) 


(L)      Preparatory 
(R) 


•  •      (P)      Affivttt&tiJie  of  Yes 


CHART     2 

L  — 2 


18  GILBERT  BOY  ENGINEERING 


TOR  USE  WITH  O5X5. 


T  &te  DA   day  WRD 

U  you.  CK    cfesctf          NSC     zttess&ie 

"*  <& 

B  te  FM  from         AHR 

R  stv  TH  Ihroigh      CXK 

W  sf/k  GA  ^  ^a^2f     GN 

TT  ?ft5f  GM  ^W  *W,   NITE 

UR  j^zzr  OB    official 

CN  c«t  OF/1     official 

BF  before  SIQ     sigtt&tuve 

BN  2^^a  ANS    &*>5i&f 

HR  &e^  MR 

HV  &2&  ML       /«w^  ^.  mile 

AF  «*&^  MU 


OK    ^//  right  ^   is  &?so  cozmttotzZy  vised 
receipt  *f 


CHART      Z      CONT'D, 


GILBERT   SIGNAL   ENGINEERING 19 

another  dot  and  dropping  one  dash,  .. This  same  plan 

is  followed  until  you  reach  number  six,  when  you  start  with  one 
dash  followed  by  four  dots  — ....  For  number  seven  write  two 

dashes  and  drop  one  of  the  dots, . . .,  and  so  on  down  the 

line  to  zero  which  is  expressed  by  five  dashes 

Chart  2  gives  the  punctuation  marks  of  the  code,  secondary 
meanings  of  several  letters  of  code  alphabet,  conventional  sig- 
nals and  abbreviations,  most  of  which  were  taken  originally 
from  the  American  Morse  Code  but  are  adaptable  to  all  methods 
of  signaling  and  are  used  by  every  practical  signalist. 

In  using  abbreviations,  no  matter  what  the  system,  always 
remember  they  are  sent  as  a  complete  word. 

THE  WIGWAG  SYSTEM 

Now  that  you  know  the  General  Service  Code,  you  are  ready 
to  make  use  of  this  knowledge  by  practicing  short  messages  with 
the  Wigwag  System. 

In  the  Army,  for  practicing  the  wigwag,  a  stick  of  light  wood 
about  18  inches  long  is  used,  and  is  called  the  wand.  The  wand 
is  held  loosely  between  the  thumb  and  forefinger  and  waved 
rapidly  to  right  or  left  to  indicate  letters  of  the  code.  A  wand 
can  be  made  easily  from  the  small  end  of  a  bamboo  pole  or  any 
light  wood. 

By  referring  to  Chart  3  you  will  see  illustrated  a  boy  holding 
the  single  stick  flag  at  position  or  ready.  He  is  standing  erect 
and  facing  squarely  the  receiving  station  which  is  represented 
on  the  chart.  The  flag  is  held  vertically  in  line  with  center  of 
head.  This  position  with  three  motions  constitutes  the  Wigwag 
System. 

On  the  chart  at  the  left  is  shown  the  first  motion,  which 
represents  the  dot.  To  make  this  motion  the  flag  is  waved 
from  position  to  right  of  sender  and  back  to  position.  This  mo- 


20 


GILBERT  BOY  ENGINEERING 


FIG.  6 

^Members  of  a  U.  S.  Marine  Signal  Corps  Company 
wigwagging  from  a  signal  tower  erected  on  roof  of 
a  building  at  Vera  Cruz,  Mexico. — Courtesy  of  U.  S. 
Marine  Corps 


tion  is  always  made 
in  a  plane  at  right 
angles  to  the  line  con- 
necting the  two  sta- 
tions as  shown  in 
center  of  your  chart. 

The  second  motion 
shown  on  right  of 
chart  gives  you  the 
dash  and  is  made  ex- 
actly as  above  only  to 
left  of  sender. 

The  third  motion 
shown  at  bottom  of 
the  chart  is  made  by 
a  wave  of  the  flag 
from  position  direct- 
ly in  front  of  sender 
to  your  feet,  and  in- 
stantly returning  to 
position  or  ready. 
This  third  motion 
represents  front  or  in- 
terval. One  front  mo- 
tion is  given  at  end 
of  each  word,  two  at 
end  of  a  sentence  and 
three  upon  comple- 


tion of  a  message. 
In  making  a  letter  of  the  alphabet— say  the  letter  Q— four 
strokes  are  made ;  i.  e.— LEFT  LEFT  RIGHT  LEFT.    It  is  not 
necessary  to  pause  at  position  in  going  from  extreme  left  to 
right  or  vice  versa.    However,  a  slight  pause  should  be  allowed 


GILBERT   SIGNAL   ENGINEERING 


21 


>'#!fp  System 


POSITION 


REAOY 


.  3TA. 


OffE   FRONT  MOTION  -  £HO 


TWO  Ff*QNT  MOTfONS  — 
£NO  OF  SENTENCE. 


THR££  FRONT  MOTIONS- 


! 


* 'MOT/ON 
CHAPT  3 


22 


GILBERT  BOY  ENGINEERING 


at  the  completion  of 
•each  letter.  Then  con- 
tinue to  finish  your  word 
and  to  give  the  front  sig- 
nal. 

A  great  deal  of  prac- 
tice is  necessary  to  be- 
come a  rapid  sender  by 
the  single  stick  flag. 
Care  should  be  taken  not 
to  foul  the  flag  on  the 
staff,  as  the  full  fly  of 
your  flag  should  always 
be  seen  by  the  receiving 
station.  This  is  some- 
times hard  to  do,  espe- 
cially on  a  windy  day, 
but  experience  will  teach 
you  how  it  is  best  to 
avoid  a  troublesome  sit- 
uation. 

The  U.  S.  Army  uses 
two  standard  outfits  for  wigwagging.  These  are  known  in 
the  Signal  Corps  as  kits.  The  two-foot  kit  contains  a  three- 
jointed  hickory  staff,  jointed  with  brass  screw  ferrules,  and 
when  fitted  together  makes  a  strong  pole  69  inches  long.  The 
flag  is  made  fast  to  pole  by  means  of  three  ties  of  tape.  These 
are  looped  through  brass  eyes  on  pole. 

Two  flags,  the  size  of  each  being  2  feet  square,  are  provided, 
one  of  bright  red  material  with  a  white  center  8  inches  square 
and  the  other  white  with  red  center.  The  flags  and  pole  can  be 
packed  in  a  canvas  kit  about  2  feet  in  length. 

The  other  outfit  used  is  the  "four-foot  kit."    In  this  outfit  the 


FIG.  7 

Boy    Scouts    sending    a    message    by    two-arm 
semaphore. — Courtesy  of  Boy  Scouts  of  America 


GILBERT   SIGNAL   ENGINEERING 


23 


pole  is  heavier  and  when  jointed  is  12  feet  in  length.  The  two 
flags  are  3  feet  9  inches  square  with  12-inch  centers;  they  are 
of  alternating  colors,  red  and  white,  as  in  the  smaller  outfit. 

THE   FLAG,  LIMITATIONS  AND  BACKGROUNDS 

The  size  of  the  wigwag  flag  to  be  used  depends  entirely  on 
the  distance  you  want  to  transmit  a  message,  and  whether  or 
not  the  receiving  station  is  equipped  with  glasses.  Under  ordi- 
nary conditions  a  flag  of  18  inches  or  2  feet  can  be  read  a  dis- 
tance of  one  mile  without  glasses  and  two  miles  with  glasses. 
This  is  the  extreme  limit  for  a  flag  of  that  size. 

Nearly  all  single  stick  flags  are  made  up  of  a  combination 
of  red  and  white  colors,  as  these  colors  usually  give  great- 
est contrast.  Red  and  orange  is  also  a  good  combination. 

Always  select  the 
color  of  your  flag  so 
as  to  give  greatest 
possible  contrast 
against  the  back- 
ground. The  white 
flag  should  never  be 
used  where  your  back- 
ground is  a  snow- 
covered  hill  or  light 
sky;  but  if  sky  is 
heavily  clouded  a 
white  flag  will  prove 
best.  The  red  flag 
should  be  used  against 
a  light  background,  of 
course.  As  some  back- 
are  very  de- 


1 


FIG.   8 

Boy  Scouts  of  Ansonia,  Conn.,  sending  a  long 
distance  wigwag  message  at  sundown. — Courtesy  of 
Boy  Scouts  of  America 


24 


GILBERT  BOY  ENGINEERING 


ceiving  at  times,  it  will  take  a  little  study  on  your  part  to  deter- 
mine the  proper  flag  to  use  for  particular  conditions. 

THE  TORCH  AND  LANTERN  WIGWAG 

At  night  the  signal  flag  is  of  no  use;  the  substitute  is  either 

the  torch  or  lantern. 

If  you  are  out  in 
the  woods  and  want 
to  send  a  message  at 
night  to  an  adjoining 
camp  and  have  no 
torch  or  lantern  at 
hand  it  is  great  fun 
to  use  firebrands.  Se- 
lected sticks  of  dry 
wood  can  be  placed 
in  the  camp  fire  and 
lallowed  to  burn  a 
minute  or  two.  The 
signalist  can  then 
send  a  message  to  his 
comrades.  It  will  sur- 
prise you  to  learn 
the  distance  you  can 
send  messages  by 
this  method.  Care 
should  be  taken  to 
get  out  of  range  of 
your  camp  fire,  as  its 
reflection  would  hin- 
der the  receiving  par- 
ty. Signaling  at  night 

A  U.  S.  Marine  semaphoring,  Haiti,  West  Indies.—       IS    always    subject    to 
Courtesy  of  U.  S.  Marine  Corps 


GILBERT   SIGNAL   ENGINEERING 


25 


FIG.  10 

U.  S.  Army  Signal  Corps  on  Mexican  Border 

more  adverse  conditions  than  by  day.  Therefore  it  is  advisable 
to  send  messages  much  slower  at  night.  Where  the  distance  is 
great,  an  additional  light  should  be  placed  in  line  with  center 
of  your  body  and  about  2  feet  from  the  ground  to  act  as  an 
indicator  or  point  of  reference  in  the  motion. 

About  the  most  practical  way  of  wigwagging  at  night  is  to. 
use  two  lanterns,  one  for  the  indicator  and  the  other  for  trans- 
mitting. Care  should  be  given  at  night  to  the  front  motion,  so 
as  to  make  it  distinct.  This  motion  can  be  simplified  somewhat 
by  moving  the  lantern  vertically  from  your  head  to  your  indi- 
cator light.  For  long  distances  you  can  fasten  a  lantern  to  a 
pole. 


26 GILBERT  BOY  ENGINEERING 

A  good  torch  can  be  made  by  nailing  an  old  tin  can  to  a  pole 
about  6  feet  long;  stuff  the  can  with  old  rags  or  waste;  pour 
over  these  a  little  oil  and  light  with  a  match.  This  will  give 
you  a  torch  that  will  burn  long  enough  to  send  any  message 
of  reasonable  length. 

WIGWAGGING  BY  SEARCHLIGHT 

The  beam  of  a  searchlight  may  be  used  for  wigwagging  at 
night  and  in  the  U.  S.  Navy  it  is  very  frequently  used.  The 
rays  of  the  light  are  directed  vertically  and  swing  from  right  to 
left  to  indicate  the  dots  and  dashes  of  the  General  Service  Code. 
All  motions  are  the  same  as  in  the  single  flag  Wigwag  System. 


Chapter  HI 

GENERAL  INFORMATION  AND  ADVICE 
TO  SIGNALISTS 

Now  that  you  have  become  familiar  with  the  General  Service 
Code  and  one  method  of  sending  it,  a  few  rules  can  be  given 
that  will  be  of  help  in  all  systems  of  signaling.  Many  bits  of 
this  advice  may  sound  military,  but  you  may  well  take  heed  of 
it  for  it  is  essential  to  practical  signaling — more  so  if  you  are 
a  Boy  Scout  or  some  day  have  occasion  to  work  with  a  military 
organization. 

Signaling,  like  all  professions,  has  its  established  terms  and 
a  correct  plan  of  procedure.  To  gain  a  full  knowledge  of  sig- 
naling it  is  necessary  that  you  become  accustomed  to  handling 
a  message  correctly. 

A  Signal  Station  consists  of  one  or  more  signalmen  operating 
as  a  unit  and  ready  at  all  times  to  send  or  receive  a  message. 
The  station  can  be  either  temporary  or  stationary. 

The  Home  Station  is  station  to  which  you  are  assigned. 

The  Sending  Station  is  station  sending  message. 

The  Receiving  Station  is  station  receiving  message. 

To  Call  a  station,  it  is  the  usual  plan  first  to  attract  attention. 
This  is  done  in  the  various  signal  systems  as  follows : — 

1.  Wigwag  system:     Succession  of  dots  and  dashes. 

2.  Semaphore  system :     Waving  flags  at  attention. 

3.  Sound  system:     Succession  of  dots  (or  toots). 

4.  Heliograph  system :     Long  and  short  flashes. 

5.  Ardois  system :     Display  of  four  white  lights. 

6.  Radio  system:     — .  —  . — 

7.  Buzzer  system :     Station  call  letter. 

(27) 


28 GILBERT  BOY  ENGINEERING 

8.  Telegraph  system :    Station  call  letter. 

9.  Flash  light  system :     Short  flashes  or  dots. 

In  addition  to  attracting  attention,  if  the  call  letter  or  letters 
of  the  station  you  desire  to  communicate  with  are  known,  the 
signal  representing  them  should  be  made  at  intervals.  It  is  very 
important  that  each  signal  station  has  a  call  of  one  or  two 
letters.  Any  letters  can  be  adopted  such  as  X  or  XY.  This  is 
essential  for  the  reason  that  you  may  be  facing  and  within  signal 
distance  of  two  or  three  stations  at  times  and  want  to  send 
only  to  one  of  these,  individually.  Note:  If  call  letter  is  un- 
known, use  the  letter  A. 

The  Receiving  Station  always  acknowledges  your  call  by 
making  R  and  its  call  letter.  After  this  acknowledgement  you 
are  ready  to  proceed  with  the  message. 

THE  MESSAGE 

The  plan  of  the  message  varies  at  times,  according  to  the 
organization ;  however,  all  messages  are  divided  in  a  general 
way  as  follows: 

1.  Preamble. 

2.  Address  to. 

3.  Text  of  message  or  body. 

4.  Address  from  or  signature. 

The  preamble  of  the  message  is  reserved  solely  for  use  of 
signalmen  dealing  with  the  message.  The  preamble  or  intro- 
duction of  a  message  consists  of  the  serial  number  of  message 
and  time  message  is  handed  in  at  station  and  accepted  for  trans- 
mission. 

All  stations  use  serial  numbers  in  handling  messages,  begin- 
ning with  number  one  and  so  on  up  for  each  twenty-four  hours, 
after  which  a  new  series  is  started.  Next  comes  the  call  letter 
of  sending  station  or  office  of  origin,  the  signalist's  personal 
signature  (all  signalmen  must  use  a  personal  signature  as,  J.  J. 


GILBERT   SIGNAL   ENGINEERING 29 

for  John  Jones,  etc.)  the  check  of  message  (number  of  words  in 
body  of  message),  and  the  class  of  message. 

To  arrive  at  the  exact  number  of  words  in  the  body  of  a  mes- 
sage this  rule  is  followed:  Include  in  count  the  address  after 
TO  and  all  words  in  body,  including  the  address  following 
FROM,  but  do  not  count  FROM  or  SIG.  if  that  term  is  used 
by  signalists.  Abbreviations,  figures  and  names  of  cities  and 
states  should  be  counted  as  one  word,  for  example :  C  X  K 
(get  reply)  is  one  word ;  South  Chicago,  Illinois,  or  So.  Chi.  111., 
is  counted  as  two  words ;  and  one-quarter  as  one  word. 

The  message  usually  indicates  whether  it  is  official  business 
(OB)  or  official  message  (OFM)  as  collect,  or  paid  message, 
urgent,  etc. 

The  Address  of  a  message  should  always  contain  enough 
words  or  information  to  insure  its  delivery. 

The  Address  FROM  should  convey  the  same  amount  of  intelli- 
gence. 

The  Double  dash  — ...  —  of  the  General  Service  Code  is 
always  used  between  the  preamble  and  address  TO;  between 
the  address  and  text;  and  between  text  and  from  or  signature. 

The  following  is  a  message  handed  in  at  a  signal  station  at 
Brown's  farm  (call  letter  B)  at  10  A.  M.  to  be  transmitted  to 
station  X  Y  (Smith's  Crossing).  Signalist  John  Jones  (J.  J.) 
takes  the  message  : — 

(To)  Bill  Smith, 

Smith's  Crossing. 

Get  your  gang  together  and  meet  me  at 
the  Stony  Creek  Bridge  at  2  P.  M.,  I  will 
bring  the  bunch,  don't  forget  your  skates, 
ice  is  one-quarter  foot  thick. 
(From)  Harry  Brown,  Brown's  Farm 

Get  reply  to  this  message.  (C  X  K) 


30 GILBERT  BOY  ENGINEERING 

After  Jones  checks  the  message  he  finds  it  contains  38  "signal 
words."  He  numbers  it  8  (as  it  is  the  eighth  message  he  has 
sent  that  day  from  his  station)  and  decides  to  send  it  by  single 
flag  wigwag.  After  getting  attention  of  station  X  Y  he  pro- 
ceeds to  send  as  follows : 

8   ( ..)   interval  or  front  TEN  front  A.  M,  front,  B 

[(Brown's  Sta.  call)  front,  C.K.  38  (message  check)  front,  JJ. 
(Jones'  signature)  front,  OF  (official  message)  front  ( — . . .  — ) 
(double  dash)  TO :  front  Bill Smith Smiths Cross- 
ing — —  get  ur  gang  together  and  

meet me at t Stony Creek bridge 

at  2   (. . )   P.M. I  will bring 

t bunch don't forget ur skates 

ice is ( — . . . — )  (double  dash  used  before  fraction) 

1    (. )   —   ( — .. — .)    (indicating  fraction  bar) 4 

( — ) foot thick (_..._)  (double  dash)  - 

SIG.   Harry  Brown  Browns  Farm  

C  X  K  (get  reply) (.  — .  — .)  (cross)  or  (. . .  — .  — )  (mean- 
ing end  of  work). 

Station  XY  acknowledges  receipt  of  message  by  O.K.  or  .  — . 
(R).  The  receiving  station  has  a  record  of  this  message  as  sent 
above  and  the  transaction  is  complete. 

Of  course,  if  you  are  not  an  expert  signalman,  to  lessen 
liability  of  errors,  it  is  best  to  spell  out  all  numerals,  fractions  and 
abbreviations. 

A  message  handed  in  at  a  signal  station  should  always  be 
looked  over,  for  an  omission  of  one  word  may  change  the 
meaning  of  the  whole  message.  The  advantage  and  importance 
of  checking  by  sender  and  in  the  recheck  by  the  receiving  sta- 
tion can  be  seen  at  once. 

Both  sending  and  receiving  stations  should  record  on  the 
message  what  system  was  used  in  handling  it.  The  date  should 
also  show,  although  the  serial  numbers,  in  a  measure,  indicate 


GILBERT   SIGNAL   ENGINEERING 31 

the  dates.    As  you  will  recall,  they  are  changed  every  twenty- 
four  hours. 

In  military  organizations  all  messages  are  considered  strictly 
confidential. 

DUTIES  OF  A  SIGNAL  UNIT 

You  have  been  told  that  a  signal  station  consists  of  one  or 
more  signalmen  operating  as  a  unit.  Where  there  is  more  than 
one,  each  must  have  his  duties  to  perform;  therefore,  it  is  ad- 
visable where  three  boys  are  operating  a  sending  station  to 
know  just  what  each  boy's  duty  is. 

First  Boy  or  Caller  takes  charge  of  the  messages,  checks  same 
and  makes  proper  entries.  When  message  is  ready  to  send  he 
calls  the  word  or  group  to 

Second  Boy  or  Sender  whose  duty  it  is  to  send  the  message  as 
called.  His  other  duty  is  to  see  that  his  sending  equipment  is 
always  in  good  condition. 

Third  Boy  or  Answer  Reader  reports  signal  as  being  answered 
and  watches  for  interruptions  from  receiving  station,  using  bi- 
noculars when  necessary.  Note :  Should  four  boys  be  operating 
a  station,  the  fourth  boy  will  act  as  a  messenger. 

INTERRUPTION  OF  MESSAGES 

At  times  signal  units  have  a  good  many  messages  on  hand 
to  dispose  of  and  have  these  messages  in  course  of  transmission 
when  a  very  important  urgent  signal  is  handed  in.  It  then  be- 
comes necessary  to  make  the  Break  Signal,  which  is  the  atten- 
tion sign  by  all  systems.  As  soon  as  the  break  is  acknowledged, 
proceed  with  the  more  important  message. 

The  Answer   Reader  should  always  be  on  the  lookout  for 


32  GILBERT  BOY  ENGINEERING 

signs  of  error  from  receiving  station  and  report  to  sender  what 
portion  of  message  has  been  missed. 

The  duties  of  these  boys  at  a  receiving  station  are  similar. 

First  Boy,  Reader  (with  binoculars),  reads  each  letter,  sign  or 
numeral,  calling  out  group  on  ending  of  each  word,  etc. 

Second  Boy,  Answerman,  stands  by  to  make  any  necessary  in- 
terruptions and  to  answer  signal  as  required. 

Third  Boy,  Writer,  writes  on  signal  form  each  group  or  signs 
as  called  out  by  the  reader. 

The  first  boy  must  be  an  expert  on  signals,  for  it  is  his  duty  to 
take  charge  of  the  signal  unit.  When  his  station  is  acting  as  a 
receiving  station,  it  is  his  business  to  read  correctly  all  messages. 
He  should  enforce  a  certain  amount  of  discipline  around  the  sta- 
tion, and  not  allow  any  unnecessary  talking,  etc.,  while  signalmen 
are  operating, 

INTERVALS 

The  intervals  of  the  General  Service  Code  were  purposely 
omitted  in  Chart  2  so  as  not  to  confuse  you  with  their  secondary 
meanings.  They  are  as  follows : 

Interval  Double  Interval  Triple  Interval 

(same  as  period)  (same  as  cross) 

Intervals  are  expressed  as  follows  in  the  various  systems: 

Interval       Double  Interval  Triple  Interval 

1.  Wigwag  front   motion  (twice)  (three  times) 

2.  Semaphore         flags  crossed  or    2  chop-chop       3  chop-chop 

machine  closed         signals  signals 


GILBERT   SIGNAL   ENGINEERING  33 

Interval      Double  Interval  Triple  Interval 

3.  Sound 

(Bell)  ...  (short  taps) 

(Whistle)  long  blast  .  — .  — . 

4.  Radio 
Flashing  light 


Heliograph 


(space) 


Buzzer  and 
Telegraph 

5.  Ardois  .  — . —  (twice)  {three  times) 

CODE  TIME 

You  have  been  informed  that,  when  a  message  is  handed  in 
at  station  and  accepted  for  transmission,  a  record  of  the  time 
is  made  and  sent  in  the  preamble.  This  code  time  serves  to 
show  how  long  a  message  has  taken  to  pass  through  the  hands 
of  the  signalmen. 

In  order  to  save  time  to  spell  out  or  to  send  code  time  by 
numbers,  the  Letter  Clock  System  is  sometimes  used. 

Chart  4  gives  you  the  letter  clock,  which  is  an  ordinary  clock- 
face  with  letters  placed  against  the  hours.  The  twelve  hours 
are  denoted  by  the  first  twelve  letters  of  the  alphabet,  omitting 
the  letter  J.  These  letters  stand  not  only  for  the  hours  but 
also  for  periods  of  five  minutes;  for  example:  A  would  be  one 
o'clock  and  five  minutes  past  any  hour,  B  two  o'clock  and  ten 
minutes  past  any  hour,  and  so  on.  AA  would  mean  one  five, 
AB  would  mean  one  ten.  To  denote  intermediate  minutes  the 
letters  RSWX  are  used  in  every  period  of  five  minutes.  Thus 
MR  means  one  minute  past  twelve ;  MS  means  twelve  two. 

The  hands  of  clock  shown  on  your  chart  show  time  to  be  four 
minutes  past  six  o'clock  and  the  letters  that  denote  that  time 
L  —  3 


34  GILBERT    BOY    ENGINEERING 


LETTER    CLOCK 


CHART 


GILBERT  SIGNAL   ENGINEERING 35 

are  FMX,  reading  in  code  time  6.04  either  A.  M.  or  P.  M.  as 
case  may  be. 

Should  a  message  be  handed  in  at  a  station  at  exactly  noon 
or  midnight  it  would  have  to  be  recorded  by  code  at  one  min- 
ute past  to  avoid  confusion.  The  message  handed  in  at  noon 
would  be  put  in  code  as  MR  P,  M.  and  at  midnight  MR  A.  M. 


Chapter  IV 
SEMAPHORE  SYSTEM 

The  word  semaphore  is  derived  from  the  Greek  word  seema, 
meaning  a  sign,  and  phero,  to  bear  or  carry.  This  system  is 
sometimes  called  brachial  telegraph,  meaning  telegraphing  with 
arms, 

THE  SEMAPHORE  MACHINE 

The  two-arm  semaphore  machine  is  used  in  permanent  sta- 
tions only,  as  it  is  not  a  portable  piece  of  signal  apparatus. 

The  semaphore  machine  is  authorized  for  use  of  the  U.  S. 
Army  at  fixed  stations  and  is  used  on  all  the  larger  ships  of 
the  U.  S.  and  other  navies. 

This  semaphore  machine  has  two  arms  or  vanes  for  forming 
the  characters  of  the  code  and  a  third  arm  or  indicator  dis- 
played on  right  of  sender  (on  left  as  viewed  by  receiver)  as  a 
point  of  reference  to  motion. 

Semaphore  machines  are  usually  about  8  feet  high,  with  arms 
of  2y<2  or  3  feet.  The  arms  are  operated  by  two  levers  which 
are  placed  on  the  machine  at  average  height  of  elbows  of  the 
body.  An  additional  lever  operates  the  indicator  arm. 

The  machine  is  painted  black  or  gray,  while  arms  and  indi- 
cator are  colored  a  light  yellow. 

For  night  use  the  machine  is  fitted  along  entire  length  of  the 
arms  with  electric  lights.  The  indicator  is  used  by  day  only  to 
indicate  direction  of  sending;  at  night,  instead  of  the  indicator,  a 
red  electric  light  is  used  at  top  of  machine.  This  light  is  screened 
to  rear,  and  if  machine  is  facing  receiving  station  squarely  it  will 

(36) 


GILBERT  SIGNAL   ENGINEERING  37 


SEMAPHORE       MACHJNE 


A  1 


d 

CRROW 


a  z 


1 


0  3 


E  5 


F  6 


JT 


G  7 


H  8 


I  9 

IX  SteCUTf. 


FRC  PARATOR  V 


M 


N 


. 


/\FFiW*»A 


T 

ACKNOWLEDGE 


u 

y 


CORNET 
U.S.  NAVY 


LETTERS 

1 


ATTEMTJ6M 


38 GILBERT  BOY  ENGINEERING 

not  be  seen.  Semaphore  machines  are  mounted  on  a  pivot  so  as 
to  turn  in  any  direction. 

Chart  5  will  show  you  alphabet  of  the  semaphore  code  ex- 
pressed by  a  two-arm  machine. 

In  addition  to  the  two-arm  machine  used  by  the  U.  S.  Army 
and  Navy  there  are  several  other  types  of  machines,  some  having 
as  many  as  six  arms.  The  most  common  of  these  is  the  four- 
arm  semaphore  used  for  transmitting  distant  signals  by  the 
International  Code  and  by  fixed  shore  stations  to  communicate 
with  ships  of  all  nations.  A  great  many  of  these  semaphore 
stations  are  found  on  the  coasts  of  Great  Britain,  France,  Italy, 
Spain  and  Portugal. 

Of  course  you  are  familiar  with  the  type  of  semaphore  used 
by  all  up-to-date  railroads,  but  do  you  know  what  these  signals 
mean? 

A  vertical  position  of  arm  means  safe — at  night  a  white  light 
is  displayed.  A  horizontal  position  of  arm  means  danger — at 
night  a  red  light  is  displayed.  The  intermediate  position  of  the 
arm  means  caution — at  night  a  green  light  is  shown. 

TWO-ARM  SEMAPHORE  BY  HAND  FLAGS 

The  method  of  semaphoring  by  hand  flags  is  used  in  both 
Army  and  Navy,  Boy  Scouts,  Girl  Scouts  and  nearly  all  organi- 
zations using  signals. 

This  system  of  signaling  has  been  more  highly  developed  in 
the  U.  S.  Navy  than  in  any  other  place  on  account  of  its  rapidity 
and  simplicity  for  the  exchange  of  messages  between  ships  of 
the  fleet. 

In  the  Army  and  other  military  organizations  this  type  of 
signaling  is  somewhat  limited  on  account  of  short  range.  The 
usual  range  for  hand  flags  of  18-inch  size  is  about  one  mile  with 
the  naked  eye,  and  is  always  dependent  upon  your  background 


GILBERT  SIGNAL   ENGINEERING 


39 


TWO-ARM      SEMAPHORE 


INTERVAL 


CORNET      U.5.M, 


ATTENTION 


DOUBLE    INTERVAL. 

IS  TWO  CHOP  CHOP 

SIGNALS. 


TRIPLE   INTERVAL 

is  THREE  CHOPCHOP 

SI6MALS 


CHOP   CHOP 


U.S.  ARMV 


U&  ARMY- NAVY 


SIGNALS 


40 


GILBERT  BOY  ENGINEERING 


TWO-ARM:    SEMAPHORE 


.A    EKKOK       1 


B 


H 


8 


I  IX  EXECUTE  9 


CMAKT     6 


GILBERT   SIGNAL   ENGINEERING  41 


TWO-ARM     SEMAPHORE 


K    NEGATIVE 


H  ANNULLING 


•  i 


H,  ACKN0H/ 


CHART 


42 


GILBERT  BOY  ENGINEERING 


TWO-ARM    5EMAFHORE 


V 


CHART      6 


GILBERT   SIGNAL   ENGINEERING  43 

and  the  light.  Much  greater  distance  is  possible,  of  course,  with 
use  of  a  telescope. 

The  size  of  flags  used  by  the  Army  are  18  inches  square,  di- 
vided diagonally  into  two  parts — one  red,  the  other  white.  The 
field  and  coast  artillery  use  the  same  size  except  as  to  colors, 
which  are  scarlet  and  orange.  The  arrangement  is  a  9-inch 
square  in  center  of  scarlet  and  a  border  of  orange  for  work 
against  dark  background.  For  light  backgrounds  the  order  is 
reversed.  The  staffs  used  are  24  inches  long. 

The  U.  S.  Navy  uses  flags  from  12  to  15  inches  square  of  blue 
with  white  square  center  for  light  backgrounds.  For  dark 
backgrounds,  a  flag  of  red  and  yellow  colors,  arranged  diag- 
onally is  used. 

Now  turn  to  Chart  6  and  study  the  different  positions.  The 
boy  is  holding  the  flags  so  as  to  make  the  characters  of  the 
alphabet.  You  will  notice  that  all  positions  by  hand  flags  are 
the  same  as  by  machine,  excepting  the  interval,  which  is  made 
by  crossing  flags  in  front  of  sender's  legs. 

The  quickest  way  to  learn  semaphoring  is  to  practice  with 
one  of  your  friends.  After  memorizing  all  the  characters  of 
the  code,  send  simple  words  to  each  other  and  later  short 
messages. 

In  making  the  characters  all  motions,  pausing  slightly  follow- 
ing each,  should  be  sharp  and  distinct  to  avoid  confusion. 

At  the  end  of  a  word  the  interval  shown  on  the  chart  and 
already  described  is  used.  At  the  end  of  a  sentence  the  double 
interval,  two  chop-chop  signals,  is  made.  At  the  end  of  the  mes- 
sage a  triple  interval,  three  chop-chop  signals,  is  used. 

The  chop-chop  signals  shown  on  your  chart  are  made  by 
placing  both  arms  vertically  to  right  of  sender  and  by  working 
flags  up  and  down  in  a  chopping  motion. 

Additional  symbols  found  in  your  chart  are  attention  or 
cornet,  numerals  follow,  signals  follow  and  letters  follow. 


44 GILBERT    BOY    ENGINEERING 

This  attention  signal  is,  of  course,  used  to  get  attention,  and 
is  made  by  agitating  the  letter  R. 

The  numerals  follow  signal  is  made  by  crossing  flags  over 
head  and  is  used  to  designate  the  fact  that  you  intend  to  use 
the  numerals  which  are  expressed  by  secondary  meanings  of  your 
alphabet  letters  A  to  J  as  shown  on  chart.  The  numerals  are 
made  by  semaphore  in  this  way  by  all  organizations  except 
the  Navy,  where  regulations  require  them  to  be  spelled  out  in 
full.  The  interval  must  be  used  following  each  numeral. 

Signals  follow  is  made  by  reversing  the  letter  L  and  is  used 
to  designate  the  fact  that  a  code  message  or  secondary  meanings 
follow. 

Letters  follow  is  used  only  by  U.  S.  Army  and  Navy  and  is 
made  the  reverse  of  the  letter  T.  It  signifies  letters  will  be  used 
to  spell  words. 

A  great  many  of  the  conventional  signals  and  abbreviations 
given  in  your  General  Service  Code  can  be  adopted  for  sema- 
phoring. To  indicate  an  error  in  semaphore  the  letter  A  is 
used  as  in  the  General  Service  Code.  As  A  already  has  a  sec- 
ondary meaning  (the  numeral  one)  it  is  necessary  to  agitate 
your  flags  a  little. 

The  conventional  interrogatory  signal  is  made  by  agitating 
the  letter  O. 

In  sending  an  official  message  by  semaphore  the  same  rules 
are  followed  as  given  in  preceding  chapter. 

No  punctuation  marks  are  given  in  the  semaphore  code  and 
if  used  they  must  be  spelled  out. 

Do  not  slur  your  letters  in  semaphoring  but  make  them 
exactly  as  shown  on  charts.  However,  now  that  you  are  be- 
coming  a  real  signalman,  it  will  not  do  you  any  harm  to  know 
that  experts  at  semaphore  signaling  sometimes  deviate  from 
the  regular  motions.  To  explain  this  in  a  practical  way,  spell 
the  following  word  without  moving  your  right  arm,  after  mak- 


GILBERT   SIGNAL   ENGINEERING 45 

ing  the  first  letter  of  word  MANILA.  Spell  BED  also  with 
right  or  left  arm  only. 

In  semaphore  signaling  when  sender  makes  an  "end  of  word" 
sign,  the  receiver  acknowledges  this,  if  the  message  is  under- 
stood, by  extending  his  arms  horizontally  and  by  waving  them 
until  the  sender  does  the  same  and  message  is  finished. 

By  machine,  the  receiving  station  fixes  his  call  letter  station- 
ary until  the  message  is  received  and  understood  and  then  the 
machine  is  closed. 


Chapter  V 
SOUND  AND  FLASH  LIGHT  SYSTEMS 

SOUND  SYSTEM.  As  early  as  the  17th  century  attempts 
were  made  to  establish  communications  by  artillery  and  mus- 
ketry firing.  The  system  of  sound  signaling,  came  into  use  at 
this  time. 

The  sound  system  is  based  on  the  General  Service  Code  and 
is  used  more  commonly  by  the  ships  of  the  Merchant  Marine 
and  the  U.  S.  Navy.  However,  due  to  its  aptness  to  cause  con- 
fusion, it  is  rarely  used  by  ships  except  in  cases  of  emergency, 
such  as  in  fogs  or  when  a  breakdown  of  other  signal  apparatus 
occurs  and  only  in  regions  unfrequented  by  other  vessels. 

Messages  are  sent  by  the  sound  system  by  use  of  steam 
whistle,  foghorn  and  bell. 

When  the  steam  whistle  is  used,  messages  are  spelled  out, 
except  in  the  case  of  the  U.  S.  Navy,  which  uses  the  Navy  Code. 

The  intervals  by  all  methods  of  the  sound  system  are  ex- 
pressed as  previously  given  in  Chapter  2,  under  intervals.  You 
will  notice  a  difference  in  signals  for  interval  in  case  of  the 
whistle  or  bell. 

In  the  case  of  the  whistle  one  long  blast  represents  the  dash 
and  a  short  one  for  dot ;  but  in  use  of  the  bell  a  continuous 
sound  cannot  be  made,  therefore  it  is  necessary  to  use  two 
strokes  to  make  a  dash  and  one  stroke  for  a  dot. 

SOUND  SIGNALS  BY  BUGLE 

The  Navy  has  lately  adopted  a  code  for  signaling  by  bugle  or 
trumpet;  this  code  was  invented  by  a  high  school  student  of 
West  Roxbury,  Mass.  The  code  is  given  you  in  Chart  7.  No 

(46) 


GILBERT  SIGNAL   ENGINEERING  47 


U.S. NAVY  BUGLE  CODE  — 


DJ7J 

J      FJJJ/  GJJ 

KJJ.T 


END  OF  MeasAOE         ? 


oJJJJ   RJJJ     sJJ       -rtt 

uj;jj 


J 

J 


OHAKT      T 


48 GILBERT  BOY  ENGINEERING 

special  musical  knowledge  is  necessary  to  sound  the  characters 
of  the  alphabet  and  numerals,  except  to  acquire  what  is  known 
by  players  of  wind  instruments  as  the  "lip,"  which  comes  very 
easy  with  a  little  practice  on  a  horn. 

You  will  notice  the  letters  of  code  are  expressed  by  not  more 
than  four  notes  and  all  numerals  by  five,  either  eighth  or  quarter 
notes.  The  relative  value  of  the  eighth  note  to  the  quarter  note 
is  one-half.  Therefore  an  eighth  note  is  made  by  a  short  blast 
on  the  horn  and  the  quarter  note  by  a  blast  twice  as  long.  The 
eighth  notes  are  the  ones  having  the  small  pennant  at  tip  of  the 
stem. 

Signals  can  be  sent  by  this  method  in  any  key,  but  it  would 
be  very  confusing  to  change  key  or  pitch  of  your  tone  in  middle 
of  message.  Avoid  slurring  the  notes  and  give  special  attention 
to  length  of  blast  signified  by  eighth  and  quarter  notes. 

Intervals  between  words  in  Bugle  Code  are  made  by  allowing 
a  space,  and  the  end  of  a  message  by  one  high  note. 

To  call  a  station  by  Bugle  Code  blow  long  blasts — followed 
by  station's  call  letter.  If  call  letter  is  unknown,  use  the  letter  A 
which  is  common  in  all  signal  systems  when  a  station  call  is 
not  known. 

To  acknowledge  receipt  of  a  message  blow  one  long  note. 

SIGNALING  BY  POCKET  WHISTLE 

All  boys  are  familiar  with  the  police  whistle  or  similar  type 
carried  by  Boy  Scouts.  The  cost  of  these  whistles  runs  from  15 
to  50  cents  and  every  boy  should  possess  one  for  signaling  or 
emergency  use  in  the  woods. 

To  signal  a  message  by  pocket  whistle  use  the  General  Service 
Code. 

The  special  conventional  signals  by  whistle  used  by  the  Boy 
Scouts  are  as  follows: 


GILBERT   SIGNAL   ENGINEERING 49 

1.  One  long  blast  means  "Silence,"  "Attention/*  "Look  out 
for  my  next  signal,"  also  used  in  approaching  a  station. 

2.  Two  short  blasts  mean  "All  right/' 

3.  A  succession  of  short,  sharp  blasts  means  "Rally,"  "Come 
together,"  "Close  in." 

4.  A  succession  of  long,  slow  blasts  means  "Go  out,"  "Get 
farther  away"  or  "Advance,"  "Extend,"  "Scatter." 

5.  Three  short  blasts  followed  by  one  long  one  from  scout 
master  calls  up  the  patrol  leaders — i.  e.,  "Leaders  come  here." 

6.  Three  long  blasts  means  "Danger,"  "Look  out." 

7.  A  succession  of  alternating  long  and  sharp  blasts  means 
"Mess  Call." 

All  whistle  signals  should  be  obeyed  as  quickly  as  possible, 
no  matter  what  work  you  may  be  doing  at  the  time. 

FLASHING  OR  OCCULTING  LIGHT  SYSTEM 

The  equipment  used  to  send  messages  by  this  system  is  the 
electric  blinker,  operating  with  a  telegraph  key,  and  the  lantern 
or  searchlight  equipped  with  shutters. 

THE  BLINKER 

The  electric  blinker  is  authorized  for  use  in  the  U.  S.  Navy 
and  is  also  used  by  many  other  navies  and  merchant  vessels. 
The  electric  lamp  is  usually  placed  at  the  peak  of  the  foremast  or 
on  yardarm  and  operated  by  a  key  from  bridge  of  ship.  Incan- 
descent lamps,  110  volts,  are  used.  These  are  used  as  a  night 
system  only  and,  like  the  other  systems,  has  its  disadvantages, 
especially  in  foggy  weather  when  used  in  a  locality  where  a 
group  of  ships  are  at  anchor  displaying  their  many  lights. 
L  — 4 


SO GILBERT  BOY  ENGINEERING 

For  sending  messages  by  blinker  the  General  Service  Code 
is  used. 

THE  ACETYLENE  LANTERN 

The  standard  night  signal  equipment  used  by  the  Army  is  the 
acetylene  lantern. 

Acetylene  is  a  pure  hydrocarbon  gas,  and  is  produced  in  the 
signal  lantern  by  bringing  water  into  contact  with  calcium  car- 
bide. The  illumination  resulting  is  about  1900  candle  power  and, 
with  the  exception  of  the  searchlight,  the  acetylene  lantern 
furnishes  the  most  powerful  form  of  night  signaling.  The  range 
obtainable  by  this  type  of  lantern  is  as  much  as  ten  miles  with 
naked  eye,  and  with  a  30-power  telescope  the  flashes  can  be  read 
for  thirty  miles. 

On  dark  and  cloudy  days  this  lantern  can  be  used  for  day 
signaling  at  a  distance  of  one-half  to  three-quarters  of  a  mile. 

SEARCHLIGHT  SIGNALING 

The  most  powerful  night  system  used  is  the  searchlight, 
which  is  equipped  with  a  shutter  and  operated  by  a  key.  This 
method  of  signaling  is  used  by  coast  artillery  corps  and  most 
commonly  by  the  Navy.  While  it  is  essentially  a  night  system, 
it  is  also  used  in  day  sending,  and  ships  at  sea  in  ordinary 
weather  have  been  able  to  send  messages  for  distances  up  to 
ten  miles. 

THE  HELIOGRAPH 

The  heliograph  is  an  instrument  designed  for  the  purpose  of 
transmitting  signals  by  means  of  the  sun's  rays. 

The  sun  being  the  most  powerful  light  in  existence,  heliograph 
flashes  can  be  sent  farther  than  by  any  other  method  of  visual 
signaling.  When  the  day  is  clear  and  the  sun's  rays  intense, 


GILBERT   SIGNAL   ENGINEERING 51 

heliograph  signals  can  be  read  up  to  forty  or  fifty  miles,  and 
even  greater  distances  are  on  record.  However,  the  normal 
range  is  around  twenty-five  miles,  and  to  obtain  longer  distances 
it  is  usually  necessary  to  operate  from  a  large  hill  or  mountain 
peak. 

The  principal  disadvantage  to  heliographing  lies  in  its  de- 
pendence upon  the  sunlight.  The  advantages  are  portability  of 
equipment ;  great  range  signals  can  be  exchanged ;  the  rapidity  of 
sending;  and  most  important  of  all  is  the  fact  that  your  signals 
cannot  be  observed  by  others  unless  they  happen  to  be  on  the 
line  of  flash  between  the  sending  and  receiving  station. 

Heliograph  instruments  vary  in  design  according  to  the  or- 
ganization using  them,  but  all  are  alike  in  principle.  The  chief 
parts  of  the  equipment  for  a  station  consist  of  one  sun  mirror, 
one  station  mirror,  a  shutter  arrangement  of  some  sort  for  inter- 
cepting the  flashes  and  a  device  for  directing  or  sighting  flashes 
on  receiving  station. 

The  Heliograph  and  Theory.  Every  boy  has  at  some  time 
taken  a  small  pocket  mirror  or  bright  piece  of  metal  from  which 
he  has  reflected  the  sun's  rays  on  a  shadowed  wall.  The  result 
on  the  wall  is  a  bright  sun  spot  or  flash  which  can  be  moved  at 
will  by  slightly  shifting  the  mirror.  As  this  flash  is  the  im- 
portant factor  in  heliographing,  it  must  be  produced  and  di- 
rected at  the  receiving  station  with  a  great  deal  of  skill. 

The  mirrors  used  in  heliographs  are  usually  not  over  4  or  5 
inches  square.  Two  mirrors  are  made  necessary  by  the  posi- 
tion of  the  sun  at  time  one  is  sending.  When  the  sun  is  at 
right  angles  to  the  line  joining  the  two  stations,  only  one  mirror 
is  used — the  sun  mirror.  With  sun  at  rear  of  operator,  the  two 
mirrors  are  required. 

With  one  mirror  the  flash  is  reflected  directly  from  it  to  re- 
ceiving station  and  with  two  mirrors  the  flash  is  reflected  from 


52 GILBERT  BOY  ENGINEERING 

the  sun  mirror  to  the  station  mirror  and  thence  to  the  receiving 
station.     (See  Figure  11,  A  and  B.) 

How  Heliograph  Operates  With  One  Mirror.  The  sun  mirror 
has  in  center  a  small  peep  hole  or  unsilvered  spot  about  one- 
quarter  inch  in  diameter.  The  sighting  device  is  about  6  or 
8  inches  to  front  of  the  mirror.  An  upright  rod  is  generally  em- 
ployed which  can  be  moved  up  and  down;  the  rod  sets  parallel 
with  edge  of  mirror  and  has  a  round  disc  on  an  arm  which 
when  turned  at  right  angles  to  rod  falls  in  line  with  center  of 
mirror. 

To  direct  the  flash  accurately  on  distant  stations,  the  operator 
sights  through  the  peep  hole  in  rear  of  mirror  and  adjusts  disc 
so  that  the  peep  hole,  disc  and  distant  station  are  on  an  exact 
line.  Then  the  sun  mirror  is  adjusted  on  its  horizontal  axis 
only,  so  that  the  "shadow  spot"  cast  by  peep  hole  falls  exactly 
on  sighting  disc.  (The  shadow  spot  can  be  found  by  placing  a 
piece  of  paper  between  mirror  and  sighting  device.)  After 
"shadow  spot"  is  located  on  disc  the  flash  is  visible  at  receiving 
station.  (See  Figure  12.) 

How  Heliograph  Operates  With  Two  Mirrors.  The  sun  mir- 
ror is  faced  towards  the  sun  and  the  station  mirror  towards 


FIG.  11 


GILBERT  SIGNAL  ENGINEERING  53 


TS 


STA. 


SHADOW  »*SC    OR  JlONTlM*    Btvice 

FIG.   12 

receiving  station.  The  station  mirror  has  a  paper  disc  pasted 
on  its  face  at  the  center.  The  sun  mirror  is  adjusted  so  that  the 
whole  of  the  station  mirror  is  reflected  into  it  and  the  unsilvered 
spot  and  reflection  of  paper  disc  accurately  cover  each  other. 

To  sight  flash  on  receiving  station  the  reflection  of  the  distant 
station  will  be  seen  in  station  mirror  and,  by  adjusting  this  so  the 
disc  covers  the  reflection  of  distant  station,  the  flash  will  then  be 
accurately  in  line. 

Intercepting  the  Flashes.  The  method  of  intercepting  flashes 
in  heliograph  is  either  with  the  improved  shutter  with  leaves 
operated  by  a  key  or  with  a  single  shutter  held  in  the  hand.  In 
either  case  uniformity  of  movement  should  be  maintained.  Be- 
cause of  the  distances  it  is  always  advisable  to  count  slowly  three 
times  for  a  dot  and  six  times  for  a  dash. 

Backgrounds.  Dark  backgrounds  should  be  selected  when 
possible  for  heliographing,  as  signals  can  be  more  readily  dis- 
tinguished. 

To  locate  a  distant  station  when  its  position  is  unknown,  take 


54 


GILBERT  BOY  ENGINEERING 


the  station  mirror  and  direct  it  towards  the  horizon,  playing  it 
in  slowly  from  right  to  left  several  times.     If  no  response  is 


FIG.  13 
U.  S.  Marines  sending  a  heliograph  message. — Courtesy  of  U.  S.  Marine  Corps 

received,  direct  it  at  a  point  near  the  home  station,  and  repeat 
this  same  process.  As  a  result  of  this  method  you  will  usually 
locate  the  station. 


GILBERT   SIGNAL   ENGINEERING  55 

If  position  of  each  station  is  known  to  the  other,  the  station 
ready  first  will  direct  its  flash  upon  the  distant  station  so  that 
that  station  may  be  able  to  adjust  its  flash  to  answer  the  signals. 

In  heliographing,  the  sun's  movement  has  to  be  watched  care- 
fully and  adjustments  made  often.  In  the  case  of  well  trained 
signalmen  these  adjustments  can  be  made  without  "breaking"  a 
message.  The  heliograph  is  best  operated  by  two  men. 

Heliograph  flashes  are  sometimes  very  hard  on  the  eyes; 
therefore  it  is  always  a  good  plan  to  smoke  the  lenses  of  the 
telescope  a  little  when  its  use  is  necessary. 

THE  ARDOIS  SYSTEM 

The  Ardois  System  for  night  signaling  consists  of  a  display  of 
red  and  white  incandescent  lamps  which  indicate  the  characters 
of  the  General  Service  Code.  The  lamps  are  arranged  in  four 
units,  each  unit  consisting  of  a  red  and  white  lamp.  The  units 
are  placed  an  equal  distance  apart  and  usually  suspended  in  a 
vertical  position  from  a  mast,  yardarm  or  staff,  in  which  case 
characters  are  read  from  top  downward.  When  it  is  necessary 
to  place  lamps  horizontally  they  are  read  by  sender  from  right 
to  left,  and  in  case  of  receiver  from  left  to  right. 

A  red  lamp  indicates  a  dot  and  a  white  lamp  a  dash.  The 
lamps  are  operated  by  a  keyboard. 

The  letters  of  General  Service  Code  are  made  by  a  single 
display;  for  example,  A  which  is  . —  would  be  made  in  the 
Ardois  System  by  a  display  of  the  red  light  of  the  top  unit  and 
the  white  light  of  the  next  unit  below.  The  letter  B  which  is 
— ...  would  be  expressed  by  a  white  light  from  the  top  unit 
and  the  next  three  units  below  would  be  red. 

Chart  8  gives  alphabet  for  the  Ardois  System,  also  conven- 
tional signals  and  numerals. 

The  numerals  of  General  Service  Code  cannot  be  used  in  the 


56 


GILBERT  BOY  ENGINEERING 


Ardoti  Alphabet 


A 

ur»r>e 

6 

B 

<} 

4 

> 
> 

c 

i 

> 

> 

D 

<j 

4 

» 
i 

£ 

| 

EKRO* 

4 
4 

> 
> 

KEPEAT 

i 

> 
> 

4 

> 

F 

o 

G 

j 

^ 
^ 

H 

< 

4 

i 

i 

I 

4 
< 

> 
> 

J 

| 

41 

n 

i 

^ 

^ 

i 

» 
> 

J 

K 

NE6ATIV2 

6 
6 

L 

< 
c 

4 

4 

i 
> 
> 
1 

M 

1 

M 

ANNUL- 

^ 
4 

i 
l 

O 

INTEffROO 

| 

P 

d 

Q.i 

| 

i 

R.2^ 

4 
< 

> 
) 

S-3 

4 

4 

> 
> 

T.* 

6 

O 

4 

< 

i 

LCP&E 

< 

> 

4 

> 

Us 

^ 

V.e 

1 
< 

1 
1 

W.7 

4 

( 

^ 

> 

X-8 

( 
< 

s 
> 

Y.9 

| 

O 

1 

< 

> 

J 

4 

s> 

{ 
i 

^ 
) 

J 

Z.O 

J 

INTERVAL 

( 

J 

CORNET 

< 
4 

i 

LETTERS 
FOLLOW 

i 
i 

| 

5IGNAL5 
FOLLOW 

t 

t 

FLASHCD 

( 

i 

J553&r 

1 
< 

[ 

STCA.VY 

^ 
i 

J 

•SSSXr 

? 

CHART     8 


GILBERT   SIGNAL   ENGINEERING 57 

Ardois  system  as  the  expression  is  limited  to  four  lamps.  There- 
fore, numerals  are  made  by  giving  secondary  meanings  to  let- 
ters of  the  alphabet  as  shown  on  the  chart. 

To  make  a  numeral,  display  the  letter  by  which  it  is  indicated, 
and  blink  or  pulsate  the  upper  light. 

In  the  case  of  letters  which  indicate  conventional  signals  the 
upper  light  is  pulsated.  The  letter  R  is  an  exception  to  this. 
When  pulsated  it  signifies  Number  2,  when  flashed  it  is  the  con- 
ventional signal  for  "acknowledge." 

The  interval  is  made  once  to  indicate  end  of  word,  twice  for 
end  of  sentence  and  three  times  for  end  of  message.  When 
interval  is  displayed  and  upper  lamp  pulsated  it  is  a  "Designator" 
signal. 

The  general  call  to  attention  is  a  steady  display  of  cornet 
WWWW.  The  cornet  is  not  used,  however,  if  call  letter  of 
station  desired  is  known.  In  answer  to  a  call,  display  call  letter 
of  station,  the  calling  station  then  proceeds  with  message. 

To  indicate  that  an  error  has  been  made  in  the  message  make 
"interval,"  the  "error,"  then  "interval"  and  then  begin  with  word 
in  which  error  occurred. 

The  letter  R  flashed  acknowledges  the  receipt  of  a  message. 

When  the  Ardois  System  is  in  use,  it  is  advisable  to  extin- 
guish all  nearby  lights  which  are  liable  to  cause  confusion  in 
signals. 

The  Ardois  System  is  authorized  for  use  by  both  Army  and 
Navy. 

THE  VERY  SYSTEM 

The  Very  System  of  night  signaling  is  used  by  Army  and 
Navy,  its  use  is  mainly  confined  to  signals  of  extreme  impor- 
tance or  when  distance  is  great. 

The  signals  are  made  by  firing  red  and  green  stars  in  the 
air  by  means  of  a  pistol  which  has  a  barrel  similar  in  gauge  to 


58 GILBERT  BOY  ENGINEERING 

the  shotgun.    The  cartridges  firing  the  stars  are  like  the  shells 
of  a  shotgun. 

This  system  is  based  on  the  dot  and  dash  code,  a  red  star  rep- 
resenting a  dot  and  a  green  star  a  dash.  This  system,  however, 
is  practical  only  for  use  with  Army  and  Navy  codes  and  there- 
fore is  not  of  any  service  to  a  boy. 


Chapter  VI 

TELEGRAPHY,  RADIO-TELEGRAPHY 
AND  TELEPHONY 

All  of  these  non-visual  forms  of  signaling  are  used  by  the 
signal  corps  of  every  modern  army.  They  are  also  the  common 
means  of  communication  in  everyday  commercial  life. 

In  all  of  the  above  methods  of  signaling  the  use  of  electrical 
currents  are  necessary  along  with  special  instruments  for  re- 
ceiving and  transmitting  messages.  The  theory  of  electric 
currents  is  a  study  in  itself.  This  subject  is  covered  in  the 
Gilbert  Electrical  Manual,  and  any  boy  wishing  to  acquire  a 
knowledge  of  electricity  and  to  apply  the  theory  to  his  apparatus 
can  do  so  by  consulting  Gilbert  Manual  of  Telegraphy  or  the 
Gilbert  Book  on  Radio  Engineering.  The  writer  will  confine 
himself  to  the  operative  side  of  signaling,  which  includes  the 
code  and  proper  form  of  handling  messages  over  these  systems. 

TELEGRAPHY 

An  American,  Samuel  F.  Morse,  invented  the  first  working 
telegraph  instrument  in  year  of  1835.  This  instrument  was 
the  recording  or  writing  type,  that  is,  it  made  marks  on  strips 
of  paper  of  dots  and  dashes  which  could  be  spelled  into  a  mes- 
sage. The  recording  instruments  are  now  obsolete  and  all 
telegraphy  is  conducted  by  sounding  instruments,  which  spell 
out  messages  by  means  of  sharp  "clicks." 

THE  AMERICAN  MORSE  CODE 

The  American  Morse  Code  is  used  on  all  land  telegraph  lines 
and  short  cables.  It  is  also  the  official  code  of  the  Army  for 

(59) 


60  GILBERT  BOY  ENGINEERING 


AMERICAN    MORSE -CODE. 


ALPHABET 

A   •  mm  B    «•••»  C  ••    •  D    mm  •• 

E    •  F    •  mmm  Gr  mmmmm  H  •  ••• 

I     ••  U    •»••»•  K  mm.  mm  U   «w 

M      £323  ME?  N       009  O     •      •  P      •  •••• 

Q   •  ooze*  R    •    •  •  8   ee«  T   mm 

U   •••»  V    •««•»  W  ••von  X    •«•• 

Y   ••    ••  2    •••    •  SL  e 

NUMERALS 
1     •«33caa»  2     •••»«•  3     •«• 

6  «••«••  6     ••«•••  7     ao9«a<DO  S    oa 

9     **••**  0    «no 

PMNCTUATION  — 

PERIOD    ••«<-»•»  COMMA    ••»•—        INTERR09ATIOM     «.«  —  «, 

HVPNEN          CHX)  J5A3M  COX>        9eMtCQLON  <S  I  ) 

50LLAV  HARKC3X)  F«ACTIOM       (/  )        OECiptAC    POINT    Gfel^do 

•HILLlW  fflAKH          CUT>  POUNXJ3,  STCRLlNCr  CPX> 

CONVCMTIOMAL.      SlOMALS 

Attention    all  opevdtova  C9)  „..-. 

~Ple3.se  sl&vt  ttw  (orj  u)heve  skill  I  start  .  ,  .  .  «    C4  ) 

Zifer^  ^  Ttit&ide  Ctnin)  ««„..— 

7  iinderst&tid,                                       COK)  ..•..«. 
Busy  on  other  z£it*e*                          C25)  .,«..  «-«,« 


COM)    .....  ...  — 


(BK)     «».•«   • 
NOTE  /—  A&bvetfialiotta    saxne  as  on 

CHART      9 


GILBERT   SIGNAL   ENGINEERING  61 


electrical  signaling  on  military  telegraph  lines,  short  cables 
and  field  lines.  This  code  is  written  on  Chart  9.  Every  signalist 
should  familiarize  himself  with  this  code  and  learn  how  it  differs 
from  the  General  Service  Code. 

The  beginner  should  thoroughly  commit  to  memory  the  signs 
representing  the  letters  of  the  alphabet,  the  numerals  and  a  few 
of  the  principal  punctuation  marks.  The  remaining  characters 
can  be  learned  afterwards  as  they  are  not  needed  by  a  beginner. 

The  Morse  Code  is  composed  of  seven  elements : 

(1)  The  dot;  (2)  the  dash;  (3)  the  long  dash;  (4)  the  space; 
(5)  the  space  between  letters ;  (6)  the  space  between  words  and 
(7)  the  space  between  sentences. 

The  dot  is  made  by  pressing  the  telegraph  key  down  for  the 
smallest  fraction  of  a  second  and  then  immediately  releasing  it. 
The  result  on  the  sounding  instrument  is  a  "click-click"  very 
close  together.  The  making  of  a  dot  involves  time,  therefore 
the  dash  is  equal  to  two  dots  and  to  make  this  the  key  is  held 

down  accordingly.  A  "click click"  sound  results.  The  long 

dash  is  equal  to  four  dots,  thus:  "click click." 

The  ordinary  space  between  elements  of  letters  is  equal  in 
time  to  a  dot,  between  the  letters  themselves  it  is  equal  to  two 
dots.  The  word  space  is  equal  to  three  dots  and  the  sentence 
space  is  equal  to  six  dots. 

Correct  Way  of  Using  the  Key.  The  most  successful  manner 
of  operating  the  telegraph  key  is  to  let  the  forearm  rest  easily 
upon  the  table,  grasping  the  key  as  shown  in  Figure  14.  The 
wrist  should  be  well  above  the  table,  the  forefinger  curved,  but 
not  held  rigid.  Let  the  thumb  rest  on  the  edge  of  knob  so  that 
a  slight  control  of  the  upward  motion  is  obtained.  The  raising 
spring  should  assist  the  upward  motion  but  should  never  be 
permitted  to  control  it.  Avoid  tapping  upon  the  key.  The 


62  GILBERT  BOY  ENGINEERING 

skilled  operator  will  manipulate  it  by  a  muscular  action  of  wrist 
and  ringers. 

Elementary  Practice  of  Code.  Constant  practice  of  making 
dots  with  uniformity  and  precision  must  first  be  acquired,  then 
dashes,  then  grouping  of  dots  and  dashes  to  form  letters  and 
words. 

The  beginner  should  commence  by  making  letters  slowly, 
giving  proper  ratio  of  time  to  the  elements  of  each  letter.  Speed 
will  come  in  time  by  persistent  drill. 

The  most  difficult  letters  of  the  code  are  C  O  R  Z  Y  and  S, 
termed  the  space  letters;  and  if  spacing  in  these  letters  is  not 
carefully  timed  they  will  be  readily  confused  with  such  letters 
as  H  I  P  and  L. 

The  letters  J  and  K,  also  numerals  9  and  7,  are  difficult  letters, 
Care  should  be  given  not  to  separate  J  into  a  space  which  would 
result  in  a  double  N. 

The  usual  tendency  is  to  make  an  F  too  long  and  an  L  too 
short. 

Practice  transmitting  from  any  miscellaneous  manuscript  at 
hand.  This  will  always  test  the  skill  of  an  operator. 

RECEIVING  TELEGRAPHY 

Receiving  is  of  course  more  difficult  to  acquire  than  sending 
and  is  mastered  best  by  having  an  experienced  operator  send 


or 

FIG.  14 


GILBERT   SIGNAL   ENGINEERING  63 

to  the  beginner  slowly,  increasing  the  speed  as  learner  becomes 
more  proficient. 

Proper  Form  of  Transmission.  A  telegraph  message  like  all 
visual  messages  must  be  checked  by  the  sender.  All  words  and 
figures  written  in  the  address,  body  of  message  and  the  signature 
are  counted.  Of  course  To  and  Sig.  are  not  counted  as  they  are 
only  indicative  terms  used  by  operator. 

In  counting  the  check  of  a  telegraph  message,  whether  in 
plain  English  or  code,  groups  or  initial  letters  are  counted  as 
one  word. 

Abbreviations  for  names  of  places,  cities,  towns  and  states 
are  counted  as  one  word,  as  if  written  in  full.  This  rule  applies 
also  to  any  other  abbreviations. 

Figures,  decimal  points,  bar  of  division  and  affixes  to  numbers, 
such  as  d,  st,  nd,  th  and  rd  will  each  be  counted  as  a  word. 

RADIO-TELEGRAPHY 

Radio-teiegraphy  or  wireless,  by  which  term  it  is  more  com- 
monly known,  was  invented  by  -Marconi  in  1901.  Since  that 
time  there  has  been  developed  many  improvements,  which  make 
the  transmission  of  messages  by  wireless  almost  as  practical  as 
by  telegraph  lines  or  cables. 

Wireless  messages  are  spelled  out  by  use  of  the  International 
Morse  or  General  Service  Code  (see  Chart  1),  the  operator 
using  a  key  like  that  used  in  telegraphing.  The  result  is  some- 
what different  from  telegraphing,  as  wireless  instruments  have 
a  humming  or  buzzing  sound  instead  of  a  "click."  The  char- 
acters of  the  alphabet  are  made  up  of  short  and  long  buzzes. 
The  receiving  is  done  through  phones. 

While  wireless  is  under  the  control  of  the  Navy  in  the  United 
States  the  government  does  not  have  exclusive  use  of  it.  A 
great  many  commercial  stations  have  been  established  and  in 


64 


GILBERT  BOY  ENGINEERING 


FIG.  15 

Boy   Scouts   of   Hartford,   Conn.,  learning  the  theory  of  wireless. — Courtesy  of  Boy 
Scouts  of  America 

this  country  alone  there  are  thousands  of  boy  experts  using 
wireless,  and  enthusiasts  are  being  added  to  the  list  daily.  Note : 
For  conventional  signals  other  than  in  General  Service  Code  see 
Gilbert  Book  on  Radio  Engineering. 


TELEPHONY 

The  most  widely  used  of  all  electrical  signal  systems  is  the 
telephone,  invented  by  Alexander  G.  Bell,  an  American.  The 
telephone  is  so  common  in  our  everyday  life  that  most  of  us 
do  not  stop  to  consider  the  interesting  principles  involved. 


Color  Charts 


GILBERT  BOY  ENGINEERING 


INDEX 

Chart  10  Flags  of  the  International  Code 

Chart  1 1  Ship  Call  Pennants  —  Call  Flags 

Chart  12  Special  Flags  of  the  U.  S.  Navy 

Chart  13  Personal  Flags 

Chart  14  Weather  Signal  Flags 


GILBERT  SIGNAL  ENGINEERING 


FLAGS  OF  THE  INTERNATIONAL   CODE 


[I 


U 


CD 


H 


ffi 


CODE  FLA&    AND   ANS. 


Q 


CHART     10 


GILBERT  BOY  ENGINEERING 


SHIP    CALL   PENNANTS 


R 


COCOR  OF 
PENNANTS  i& 
BASED  ON  DOT 
AND  DASH  CODE 


X — 


C 


«T 


U 


K _ 


Q 


OASH.YELLOW 

DOT     ,  KED 

SLOB  ,  «  ere ATS 
p*eeeoiMO  COL. 


CALL    FLAGS 


6 


PHI 


ffl 


w 


CHART     11 


GILBERT  SIGNAL  ENGINEERING 


SPECIAL 


OF  THE    U.S.  NAVY 


EB 


NUMERALS 


Q-ENERAL    RECALL 
(JOAT   RECALL 


J 


PREPARATORY 


AFFIRMATIVE 


ANNULLING 


INTER  ROflATORT 


DISPATCH 
BREAK     DOWN 
MAN    OVERBOARD 


1ST. 

REPEATER 


Bo. 

REPEATER 


REPEATER 


QUARANTINE 


SQUADRON 


CONVOY 
POSITION 
DIVISION  <?diOE 


MEAL 

FULL    SPEED 


RED    CROSS 


BATTLE 
EFFICIENCY 


POWDER 

FLAO- 


ANSWERING 

AND    . 
DIVISIONAL  PT. 


CHART     12 


GILBERT  BOY  ENGINEERING 


U.S.  MAN  O  WAR.     AND 
MERCHANT 


UNION    JACK. 


CONSULAR 
FLACr 


SECY.  OF  THE 
NAVY 


A55T.  3ECY. 
CF  THE  NAVY 


ADMIRAL 


VICE 
ADMIRAL 


REAR  ADMIRAL 
5f  NiOl?  IN  RAN*. 


PEA*  ADMIRAL 
JUNIOR  in  RANK 


5ENIOR    OFF- 


COMMISSION 
PENNANT 


TORPEDO 

FLOTILLA 


NAVAL 

MILITIA 


NAVAL  HILJTJA 
COMMODORE 


NAVAL  MILITIA 
COMMISSION  PT. 


ci.ua 

PP  NNANT 


-|  OWNERS 
DINNER 
I  FLA& 


REAR 
COMMO- 
DORE 


COMMODORE 


CHART  13 


GILBERT  SIGNAL  ENGINEERING 


WEATHER   SIGNAL  FLA&S 


RA.IN   OK  SNOtnt  T£HP£KATUKE  CL£AKf  OK 

FLAG  FAIK 


LOCAL  RAINS  COLO    WAVES 

STORM   SIGNAL  FLAGS 
AND    NJGHT    LANTERNS 


SHALL   CRAFT  N.E.  STORM  S.E.STOKM 


s.w.  STORK 


*  *    *•.>**„     *^  • 
CHART      14 


GILBERT   SIGNAL    ENGINEERING 


65 


In  speaking,  the  vocal  cords  cause  air  vibrations,  which,  fall- 
ing upon  the  eardrum  are  recognized  by  the  auditory  nerves  as 
speech.  When  these  vibrations  are  transmitted  into  a  telephone 
instrument,  they  are  caught  by  the  sensitive  diaphragm, 
changed  into  electrical  vibrations,  carried  along  the  telephone 
wire  to  the  receiving  station  and  reproduced. 

Note:  See  Gilbert  "Sound  Experiments"  and  Manual  on 
Telephone. 

THE  TELEPHONE  FOR  SIGNAL  PURPOSES 

When  signal  stations  are  connected  by  telephone,  messages 
are  of  course  sent  by  this  means,  it  being  much  more  handy. 


L  — 5 


FIG.  16 

U.  S.  Army  Signal  Corps  field  radio  station  somewhere  in  France. 


66 GILBERT    BOY    ENGINEERING 

The  difficulty  arising  in  telephonic  messages  is  the  confusion 
of  certain  letters  of  the  alphabet  having  like  sounds  when  spoken 
by  word  of  mouth. 

To  provide  a  ready  means  of  distinguishing  similar  sounding 
letters,  a  code  of  conventional  signals  is  authorized  for  military 
purposes  and  should  be  used  especially  when  codes  are  being 
sent.  These  conventional  signals  are  as  follows: — 

A— Able  N— Nan 

B— Boy  O— Oboe 

C_Cast  P— Pup 

B_Dog  Q— Quack 

E — Easy  R — Rush 

F— Fox  S— Sail 

G — George  T — Tare 

H— Have  U— Unit 

I— Item  V— Vice 

J— Jig  W— Watch 

K— King  X— X-ray 

L— Love  Y— Yoke 

M— Mike  Z— Zed 


To  give  an  example  of  the  proper  use  of  this  code  we  will 
suppose  an  important  message  is  being  telephoned  to  a  station 
and  the  receiving  operator  cannot  clearly  understand  certain 
words  such  as  directory,  or  the  word  translation.  To  make 
these  words  clear  the  operator  would  spell  directory  out  slowly 
Dog-Item-Rush-Easy-Cast-Tare-Oboe-Rush-Yoke.  The  word 
translation  would  be  spelled  out  likewise.  From  this  code  a 
clear  understanding  would  undoubtedly  result. 


GILBERT   SIGNAL   ENGINEERING 67 

THE  SERVICE  BUZZER 

The  Service  Buzzer  is  a  portable  piece  of  signal  equipment 
especially  adapted  to  the  needs  of  the  Army  Signal  Corps.  It 
can  be  readily  attached  to  either  telephone  or  telegraph  lines  and 
used  as  a  telephone  or  for  sending  Morse  or  General  Service 
Code  telegraphic  signals. 

When  service  buzzer  is  used  in  the  latter  form  the  signals  are 
received  in  a  telephone  receiver  in  form  of  a  high-pitched  hum 
very  similar  to  wireless  signals. 

Signals  have  been  exchanged  between  two  buzzer  outfits 
even  after  wire  connecting  the  stations  has  been  cut  in.  The 
instruments  were,  of  course,  grounded. 

The  mechanism  of  the  buzzer  is  very  simple,  so  simple  in 
fact  that  any  boy  can  make  a  practical  outfit  for  Field  Service 
Signaling  by  following  the  suggestions  given  in  this  book  on 
page  102. 


Chapter  VII 
THE  SIGNAL  TOWER 

The  Tower  of  Babel  served  as  a  rallying  point  and  in  all  prob- 
abilities was  the  first 
signal  station.  Later 
examples  of  old  sig- 
nal towers  are  those 
built  by  the  Chinese 
along  the  wall  of 
China.  Today,  how- 
ever, the  modern  sig- 
nalmen do  not  build 
such  substantial  tow- 
ers, as  the  up-to-date 
armies  are  mobile  and 
consequently  when  a 
signal  tower  is  re- 
quired a  portable  one 
or  a  hand-made  affair, 
which  can  be  erected 
in  a  few  minutes  by 
field  signal  troops,  is 
used. 

The  boy  signalist 
wanting  to  establish  a 
visual  station  must 
first  select  the  site  so 
it  is  perfectly  in  view 
of  receiving  station 
and  with  a  uniform 
FIG.  17  background  for  all 

Signal  tower  erected  at  a  boy  Scout  Camp. — Cour-       ci'rrnplQ         TVii* 
tesy  of  Boy  Scouts  of  America  Signals.         1  ne 

(68) 


_  GILBERT   SIGNAL   ENGINEERING  _  69 

station  is  the  best  judge  of  the  proper  location  and  background 
for  the  signal  tower. 

In  locating  a  military  station  secrecy  is  of  vital  importance, 
and  for  this  reason  the  tower  is  usually  camouflaged  by  shrub- 
bery or  erected  behind  foliage  so  the  platform  of  tower  is  barely 
exposed. 

The  following  table  gives  distances  of  the  visible  horizon  or 
how  far  an  object  at  sea  level  can  be  seen.  When  observer's 
eye  is  : 

5  feet  above,  the  distance  is    2.7  miles 
10    "         "         "          "          "     3.8      " 
15     "         "         "  "    4.7      " 

o/~v        ((  (S  t<  ft  it         C   A  f( 

25    "         "         "          "          "    6.1 

30    "         "         "          "          "    6.7      " 

or       «  <f  «  ft  tf       *j  o         « 

Af\          ((  (I  ((  ((  ((          O  « 


100    "         "         "          "          "  12.2      " 
150    "         "         "          "          "  15 
200    "         "         "          "          "  17.3 

It  can  readily  be  seen  from  the  above  table  that  an  observer 
whose  eye  is  25  feet  above  sea  level  can  distinguish  an  object 
at  a  distance  of  6.1  miles  provided  the  object  is  at  sea  level. 
Now  should  the  object  itself  be  elevated  15  feet  its  visibility 
would  be  increased  to  6.1  miles  and  4.7  miles,  equaling  10.8  miles. 

To  receive  visual  signals  at  the  distances  given  above,  a 
telescope  is  used. 

SUGGESTIONS  FOR  ERECTING  A  SIGNAL  TOWER 

The  height  necessary  for  building  a  signal  tower  should  be 
calculated  according  to  distance  between  points  of  communica- 


70 


GILBERT  BOY  ENGINEERING 


FIG.  18 
A  natural  point  of  vantage  for  signaling. — Courtesy  of  Boy  Scouts  of  America 

tion.  When  possible,  natural  points  of  vantage  should  be  used, 
such  as  the  roof  of  a  building  or  a  platform  built  in  a  tree. 
Sometimes  several  trees  can  be  found  close  together  which  can 
be  connected  by  stringers  and  a  platform  laid  around,  to  which 
a  rail  can  be  added.  A  ladder  would  lead  up  to  the  staging  to 
complete  the  arrangement. 

Where  no  natural  supports  can  be  found,  it  will  be  necessary 
to  build  a  tower.  A  substantial  tower  can  be  erected  by  using 
either  three  or  four  uprights  for  supporting  the  platform.  The 
uprights  can  be  made  of  finished  lumber,  using  2x4  pieces  or 
heavier  ones,  depending  on  height  of  tower  wanted. 

The  drawing  on  page  71  suggests  a  tower  made  of  three 
selected  trees  cut  to  lengths  of  18  feet.  These  are  placed  in  the 
ground  about  \l/2  or  2  feet,  the  arrangement  of  placing  being 
triangular  and  8  feet  apart.  The  uprights  are  leaned  in  at  the 
top  and  tied  4  feet  apart,  on  which  a  platform  is  laid  which  will 
accommodate  two  signalmen.  The  platform  can  be  made  of 


GILBERT   SIGNAL   ENGINEERING 


71 


FIG.  19 

Illustrating    method    of    constructing    signal    tower 


72 


GILBERT  BOY  ENGINEERING 


boards  or  else  straight  limbs  of  trees  spiked  to  the  cross  girders. 
At  a  distance  of  5  feet  apart  cross  ties  should  be  spiked  to 
make  the  tower  as  rigid  as  possible. 

A  row  of  cleats  nailed  to  one  of  the  uprights  does  very  well 
for  the  ladder. 

SECRET  CODES  AND  CIPHERS 

Both  the  Army  and  Navy  have  their  code  books,  which  are 
especially  adapted  to  military  needs  and  insure  both  secrecy  and 
economy  of  words  in  signaling.  These  codes  are  confidential 
except  to  those  in  service  of  the  Government. 

The  land  telegraph  and  cable  companies  also  issue  code  books 
from  time  to  time  to  their  customers,  not  so  much  for  the  reason 


GILBERT   SIGNAL   ENGINEERING 


73 


FIG.  21 

of  secrecy,  as  for  economical  benefit  of  the  messages.  These 
code  books  can  sometimes  be  obtained  and  will  serve  very  well 
for  all  classes  of  signals. 

So  the  boy  signalman  will  not  be  handicapped  for  the  want  of 
a  secret  code,  the  writer  will  suggest  the  cipher  disc  which  is 
used  by  the  signal  corps  and  another  improvised  method  of 
using  the  cipher. 

THE  CIPHER  DISC 

The  cipher  disc  used  by  the  signal  corps  is  a  simple  but  in- 
genious device  pictured  in  drawing  on  opposite  page.  It  con- 
sists of  two  circles  of  cardboard,  one  smaller  than  the  other. 
These  are  joined  at  center  so  as  to  revolve.  The  inner  circle  is 
lettered  around  the  edge  with  small  letters  and  the  outer  circle 
with  capital  letters  of  the  alphabet. 

The  alphabet  reads  from  right  to  left  on  outer  circle  and  left 
to  right  on  the  inner  circle. 

The  letter  A  on  inner  circle  indicated  by  the  arrow  is  the  key 
letter  to  the  cipher.  The  purpose  of  this  cipher  is  only  to  trans- 
pose one  letter  of  the  alphabet  for  another,  thus  the  message 
WE  BREAK  CAMP  AT  SUNRISE  when  read  from  the  disc 


74 GILBERT  BOY  ENGINEERING 

pictured  would  be  sent  and  received  as :  JB  EOBFV  DFTQ  FM 
NLSOXNB.  It  is  of  course  understood  by  reader  that  the 
letter  F  would  have  been  agreed  upon  by  the  sending  and  re- 
ceiving stations  prior  to  time  this  message  was  sent. 

Any  letter  can  be  agreed  upon  between  sending  and  receiving 
station  and  then  the  key  letter  A  is  set  opposite  on  disc  to  en- 
cipher the  message. 

All  numbers  are  spelled  out  when  sent  in  a  cipher  message. 

It  is  apparent  to  the  reader  that  this  method  is  not  absolutely 
unreadable  to  any  one  who  would  take  the  time  to  figure  out  the 
key;  however,  when  used  in  connection  with  a  code,  it  can 
be  made  much  more  complicated  to  any  one  desiring  to  read 
your  message. 

The  above  method  of  sending  cipher  could  be  used  with  the 
6eneral  Service  Code  which  was  in  existence  prior  to  the  adop- 
tion of  the  International  Code  of  dots  and  dashes. 

The  old  General  Service  Code  is  written  as  follows : 

A— 22  J— 1122  S— 212 

B— 2112  K— 2121  T— 2 

C— 121  L— 221  U— 112 

D— 222  M— 1221  V— 1222 

E— 12  N— 11  W— 1121 

F— 2221  O— 21  X— 2122 

G— 2211  P— 1212  Y— 111 

H— 122  Q— 1211  Z-.2222 

I— 1  R— 211  &— 1111 

tion— 1112 

ing— 2212 

end  of  word — 3 

end  of  sentence — 33 

end  of  message — 333 


GILBERT   SIGNAL   ENGINEERING 


75 


The  foregoing  code  is  used  with  the  various 
signal  systems  as  follows : 

Wigwag  or  single  flag — one  would  be  to  right 
and  two  to  left,  three  would  be  expressed  by  the 
front  motion. 

Ardois  System — one  would  be  red  light  and 
two  white  light,  a  space  would  be  made  for  end 
of  word,  etc. 

Sound  System,  by  whistle,  bell  and  foghorn — 
one  would  be  indicated  by  a  short  blast  or  taps 
and  three  likewise. 

Telegraph,  Wireless  and  Flash  Light  System 
— one  would  be  made  by  one  click,  buzz  or 
flash,  two  by  two  clicks,  buzzes  or  flashes  and 
three  made  in  same  way  using  three. 


zo 


T 


Z5 


Zt> 


Z7 


-fr34 


3Z 


tt 


37 


L* 


4-1* 


5-0 


4-Si 


HOW  TO  MAKE  A  CIPHER  OUTFIT 

A  practical,  yet  simple  cipher  can  be  made  by 
first  obtaining  several  pieces  of  ordinary  flat  pic- 
ture moulding  like  those  shown  in  Figure  21. 
These  pieces  will  slide  parallel  to  each  other;  one 
piece  should  be  at  least  14  or  15  inches  in  length, 
while  the  other  can  be  just  half  that  length. 

Next  take  white  ruled  paper  and  paste  along 
flat  surfaces  of  moulding,  the  ruling  or  lines  of 
paper  should  be  about  ^  inch  apart. 

Fifty-two  spaces  are  necessary  for  the  long 
piece  and  the  alphabet  is  written  twice,  back- 
wards, in  small  letters,  starting  from  top  as 
shown  in  Figure  22,  these  letters  are  numbered 
from  1  to  52. 


FIG.  22 


76 GILBERT  BOY  ENGINEERING 

The  short  piece  of  moulding  is  lettered  with  capitals  starting 
with  A  at  top,  going  down  or  the  reverse  of  the  lettering  on  the 
longer  piece,  which  starts  at  bottom  going  up. 

The  number  10  on  the  small  piece  and  the  opposite  number 
on  the  long  piece  are  used  as  keys  to  cipher. 

Method  of  Using  Cipher  Outfit.  By  referring  to  Figure  22  it 
will  be  seen  at  once  that  to  change  the  cipher  all  that  is  neces- 
sary is  to  shift  the  small  piece  of  picture  moulding  up  or  down. 
Each  sending  and  receiving  station  would  have  this  outfit  handy, 
and  to  send  a  message  the  following  procedure  should  be  kept 
in  mind. 

Encipher  or,  that  is,  put  your  message  into  cipher  from  capi- 
tals to  the  opposite  small  alphabet. 

To  decipher  a  message  at  receiving  station  use  the  reverse 
method. 

To  give  the  receiver  the  proper  key  to  cipher;  this  can  be 
done  by  signaling  the  key  in  the  preamble  of  your  message ;  for 
example,  the  message :  "WE  BREAK  CAMP  AT  SUNRISE" 
would  be  sent,  if  taken  from  Figure  22,  as  follows:  (Key) 
10—27  QI  LVIMC  KMAX  MT  USZVEUI. 


Chapter  VIII 
MARITIME  SIGNALING 

United  States  Maritime  Signaling  is  divided  into  two  branches : 
that  of  the  Merchant  Marine  and  that  of  the  Navy.  The  signal 
methods  of  the  Merchant  Marine  apply  in  all  cases  to  privately 
owned  yachts,  power  boats  and  other  small  craft  having  use  for 
a  signal  system. 

To  be  well  versed  in  Maritime  Signaling  it  is  necessary  for 
a  signalist  to  know  wherein  the  methods  differ  between  U.  S. 
merchant  vessels  and  ships  of  the  U.  S.  Navy. 

U.  S.  Merchant  Marine  Signaling.  The  methods  of  signaling 
in  the  U.  S.  Merchant  Marine  are  based  entirely  on  the  Interna- 
tional Code  of  signals,  which  is  the  result  of  many  years  of 
work  on  the  part  of  the  International  Marine  Conference. 

The  International  Signal  Book  is  used  by  all  vessels  through- 
out the  world,  both  merchant  and  men-of-war,  thus  enabling  all 
ships  to  carry  on  communications  by  signals,  even  without  the 
knowledge  of  one  another's  language. 

Every  signal  in  the  International  Signal  Book  has  the  same 
meaning  in  any  language. 

Signals  are  sent  from  the  International  Signal  Code  by  means 
of  the  following  systems : 

Flag  Hoists,  International  Morse  Code,  which  is  same  as  Gen- 
eral Service  Code,  International  Flag  Waving,  Colombs  Sound 
and  Flashing  System  and  International  Distance  Signals. 

The  most  general  method  of  signaling  by  vessels  is  by  means 
of  flag  hoists  in  which  the  International  Code  flags  are  employed. 

(77) 


78  GILBERT  BOY  ENGINEERING 

There  is  nothing  that  gives  a  poorer  impression  to  expert 
signalmen,  or  those  who  know,  than  to  observe  the  misuse  of 
flags  in  signaling.  For  this  reason  the  writer  will  acquaint 
you  in  a  general  way  with  a  few  nautical  terms  relating  to 
flag  hoist  signals  and  correct  form  of  handling  flags. 

FLAGS  AND  CORRECT  WAY  OF  USING 

The  Hoist  of  any  flag  is  the  side  fastened  to  flagstaff  or  line 
holding  it. 

The  Fly  of  a  flag  is  at  right  angles  to  the  hoist.  (See  Figure 
23.) 

A  Hoist  of  flags  is  a  number  of  signal  flags  on  one  line  or 
hoist. 

The  lines  by  which  a  signal  flag  or  flags  are  hoisted  are  called 
halyards. 

That  part  of  halyard  which  is  attached  to  upper  hoist  of  flag 

running  through  pulley  or 
block  is  termed  the  down 
haul. 

That  part  of  halyard 
which  is  connected  to  the 
lower  hoist  of  the  flag  or 
flags  is  termed  the  tail.  (See 
Figure  23.) 

Flag  signals  on  merchant 
ships  are  usually  hoisted  to 
the  most  convenient  position 
on  the  yardarm  or  mast 
from  which  signals  can  best 
be  seen  and  distinguished. 
However,  on  most  of  the 
FIG.  23  larger  ships  a  special  signal 


GILBERT   SIGNAL   ENGINEERING 


79 


CARKICK  BEND 

FIG.  24 


yard  is  used  on  the  foremast 
which  is  situated  ahead  of  the 
ship's  funnels.  The  signals  are 
not  then  obscured  by  smoke  ex- 
cept in  a  case  where  receiving 
ship  is  dead  astern. 

Signal  flags  are  flown  from 
either  Port  (left  side  of  a  ship) 
signal  yardarm,  or  Starboard 
(right  side  of  a  ship)  signal  yard- 
arm  according  to  position  of  the 
receiving  ship. 

A  flag  is  said  to  be  close  up 
when  hoisted  to  its  limit  on  a 
yardarm  or  mast  and  at  dip 
when  only  hoisted  two-thirds  of  the  way  up.  (See  Figure  25.) 

The  Peak  of  a  mast  is  extreme  top  point.  All  signal  and 
special  distinguishing  flags  vary  in  size  and  shape;  however, 
in  regard  to  shapes,  a  way  of  classifying  as  to  proper  names  can 
be  found  by  consulting  Figure  27. 

Signal  flags  are  fastened  on  the  halyards  by  means  of  a  ring 
at  the  upper  end  of  the  hoist  of  flag  and  a  snap  hook  at  lower 
end.  They  may  be  tied  to  halyards  by  means  of  a  single  carrick 
bend.  (See  Figure  24.)  The  last  method  is  clumsy  and  slow. 
All  of  the  up-to-date  merchant  lines  and  navies  that  have  a 
great  many  signals  to  handle  use  rings  and  hooks. 

FLAGS  OF  THE  INTERNATIONAL  CODE 
AND  HOW  USED 

The  International  Code  flags  are  twenty-six  in  number — one 
for  each  letter  of  the  alphabet  and  also  a  code  pennant,  all  of 
which  are  pictured  on  Chart  10.  (See  special  section  of  colored 
fla^s.) 


80 


GILBERT   BOY  ENGINEERING 


One-flag  signals  B,  C,  D,  L,  P,  Q  and  S  hoisted  singly  have 
a  special  significance.  The  code  pennant  over  each  indicates 
that  they  are  signals  of  a  general  nature  and  of  frequent  use. 

Code  flags  hoisted  singly  after  numerals  signal  Number  1  refer 
to  numeral  table  in  Code  Book,  as  do  also  two-flag  signals  with 
code  pennant  hoisted  under  them. 

Two-flag  signals  without  code  flag  are  urgent  and  important 
signals;  with  the  code  flag  hoisted  over  them  they  are  time, 
latitude,  longitude,  barometer  and  thermometer  signals.  Three- 
flag  signals  express  points  of  the  compass,  money,  weights  and 
measures  and  also  other  signals  required  for  general  communica- 
tion. Four-flag  signals  with  a  burgee  (A  or  B)  uppermost  are 
geographical  signals;  with  C  uppermost  they  are  spelling  or 
vocabulary  signals;  with  G  uppermost  they  are  names  of  men- 


YARD 


FIG.  25 


GILBERT   SIGNAL   ENGINEERING  81 

of-war;  with  a  square  flag  uppermost  they  are  names  of  mer- 
chant vessels. 

The  following  are  meanings  given  single  flags  already  men- 
tioned : 

B.  Am  taking  on  (or  unloading)  explosives. 

C.  Yes  or  affirmative. 

D.  No  or  negative. 

L.  I  have  (or  have  had)  infectious  disease  aboard. 

P.  I  am  about  to  sail ;  all  persons  report  on  board. 

Q.  Have  clean  bill  of  health,  but  liable  to  quarantine. 

S.  I  want  a  pilot. 

Single  flags  are  sometimes  used  as  signals  from  a  towing 
ship  to  ships  in  tow ;  the  meanings  when  used  thus  do  not,  how- 
ever, correspond  in  any  way  to  above  signals. 

METHOD  OF  SIGNALING  WHEN  NO  OTHER  SHIPS 
ARE  IN  SIGHT 

Example :  Ship  A  wants  to  signal  ship  B.  Ship  A  will  hoist 
her  ensign  (national  colors)  over  the  code  pennant  but  not  on 
the  same  halyard.  If  hoisted  at  same  mast  as  succeeding  signal 
the  methods  will  interfere.  As  soon  as  ship  B  makes  out  the 
attention  signal  she  will  answer  by  hoisting  the  code  pennant 
at  dip ;  then  ship  A  proceeds  with  signals,  first  hauling  down 
the  code  flag,  and  when  completed  ship  B  acknowledges  by 
hoisting  the  code  pennant  close  up  and  leaves  it  there  until  ship 
A  hauls  down  the  hoist  of  signals  after  which  she  lowers  it  to 
dip,  and  awaits  the  next  signal. 

When  ship  A  has  completed  her  signals  she  hauls  down  the 
ensign  and  the  other  ship  hauls  down  the  answering  pennant 
(code  pennant). 
L— -6 


82 GILBERT  BOY  ENGINEERING 

All  flag  hoists  are  read  from  top  down  and  never  exceed  four 
to  the  hoist. 

In  case  several  ships  are  in  sight  and  ship  A  wishes  to  signal 
ship  B,  she  will  attract  attention  of  B  by  either  of  two  ways; 
the  first,  is  to  hoist  B  ship's  distinguishing  letters  or,  second,  to 
hoist  the  two-letter  signals  which  indicate  direction  the  ship  she 
wishes  to  call  is  traveling. 

All  vessels  are  supposed  to  display  their  distinguishing  call 
letters  when  passing  at  sea. 

DISTANT  SIGNALS 

When  in  consequence  of  distance,  wind  or  weather  preventing 
the  code  flags  from  being  seen,  an  alternative  method  of  signal- 
ing  is  used,  which  is  known  as  distant  signals. 

There  are  three  ways  of  making  distant  signals: 

1.  By  means  of  the  Fixed  Coast  Semaphore. 

2.  By  means  of  square  flags,  pennants  and  whefts. 

3.  By  means  of  cones,  balls  and  drums. 

Calm  weather  and  when  wind  is  blowing  from  and  towards 
the  receiving  station  are  the  reasons  that  make  it  difficult  to 
make  out  the  colored  flags  of  the  International  Code.  For  this 
same  reason  the  method  of  distant  signaling  by  means  of  square 
flags,  pennants  and  whefts  is  not  as  preferable  as  by  the  cones, 
balls  and  drums.  A  wheft  is  any  flag  tied  in  center  to  halyards ; 
therefore  this  system  is  mostly  used. 

Chart  15  gives  the  distant  signal  alphabet  by  balls,  cones  and 
drums. 

The  shapes  are  made  by  stretching  canvas  over  pieces  of  light 
wood  or  metal  forms,  the  canvas  is  as  a  rule  then  painted  black. 

The  signals  are  made  from  International  Signal  Book  and 
hoists  are  read  from  top  down  same  as  the  flags. 


GILBERT  SIGNAL   ENGINEERING 


83 


DISTANT    SIGNAL     ALPHABET 


M 


N 


0 


U 


CHART     15 


Q 


84 


GILBERT  BOY  ENGINEERING 


For  convenience  in  their  use  the  shapes  representing  the  let- 
ters have  been  arranged  in  numerical  order.  The  letters  A  to  G 
begin  with  one,  the  letters  H  to  U  begin  with  two,  and  the  let- 
ters V  to  Z  begin  with  three. 

Distant  signals  by  Fixed  Coast  Semaphore  are  made  by  a  sem- 
aphore machine.  The  position  of  the  arms  indicate  numbers 
which  are  translated  from  the  International  Signal  Book.  This 
method  is  only  employed  by  shore  stations  and  not  by  ships. 

INTERNATIONAL  FLAG  WAVING  SYSTEM 

The  International  Flag  Waving  System  is  done  by  a  single 
stick  wigwag  flag  and  the  International  Morse  Code  is  used. 
However,  the  method  of  making  dots  and  dashes  is  different 
from  the  U.  S.  Army  and  Navy  Wigwag  System. 

The  dot  is  made  by  a  short  sweep  of  flag  over  the  head  of 
sender  and  a  dash  by  a  long  swing  of  the  flag. 


Chapter  IX 
U.  S.  NAVY  FLAG  SIGNALS 

The  flag  signal  system  of  the  Navy  is  in  all  probability  the 
most  important  of  all  day  signal  methods.  It  has  the  advantage 
over  the  two-arm  semaphore,  either  hand  flags  or  machine 
method,  and  the  wigwag  which  are  the  other  day  systems  used 
by  the  Navy  and  which  have  already  been  explained. 

The  advantage  of  flag  signals  in  the  Navy  is  the  great  range 
and  its  adaptability  to  fleet  manoeuvering  and  battle  tactics. 

The  flag  signals  are  made  by  hoists  transmitting  the  Navy 
Flag  Code,  this  flag  code  can  also  be  sent  by  all  the  other  signal 
methods  used  in  the  Navy. 

When  flags  are  necessary  for  intercommunication  between  the 
U.  S.  Army  and  all  merchant  ships,  the  International  Flag  Code 
is  used. 

The  term  "break"  or  flag  is  "broken"  will  come  up  in  connec- 
tion with  Navy  flag  signaling,  so  it  will  be  well  to  acquaint  you 
with  the  proper  way  of  making  up  a  signal  flag  for  breaking. 

There  are  several  ways  to  do  this,  but  the  following  plan,  if 
followed,  will  prove  the  most  reliable : 

Figure  26  (A)  shows  a  signal  flag  lying  flat  on  the  deck  ready 
to  be  made  up  for  the  "break."  To  do  this  the  flag  is  folded 
on  dotted  lines  1  and  2  and  then  rolled  towards  the  hoist  as  in 
B,  after  which  the  tail  line  is  laid  on  top  of  rolled  flag  in  form  of 
a  loop.  The  free  end  of  line  is  then  wrapped  securely  around 
the  roll  and  over  the  loop  by  a  number  of  turns  and  again  looped 
into  the  end  of  other  goose  neck  (see  C)  and  drawn  tight,  which 
serves  to  clinch  the  tail  line. 

(85) 


86 


GILBERT  BOY  ENGINEERING 


The  flag  is  then  ready  to  hoist  as  in  D,  after  which  it  can 
be  broken  by  simply  giving  a  sharp  tug  on  the  tail  line. 

The  foremast  is  principally  used  for  signaling  by  naval  ships, 
except  in  the  case  of  a  flagship  which  flies  her  signals  from  the 


FLAG- 


GILBERT   SIGNAL   ENGINEERING  87 

main  mast.    The  signal  yards  in  either  case  are  usually  provided 
with  three  to  six  signal  halyards  on  each  port  and  starboard  side. 
The  peak  of  a  mast  on  a  naval  ship  is  usually  termed  the 
truck. 

HOW  NAVY  SIGNALS  ARE  EXECUTED 

The  General  Signal  Book  of  the  U.  S.  Navy  contains  a  list 
of  signals  known  as  the  Navy  Flag  Code.  This  book  is  divided 
into  various  parts,  some  of  which  are  very  confidential  and  are 
in  the  hands  of  only  the  higher  officers. 

The  method  of  making  the  signals  is  alike  no  matter  from 
what  section  or  volume,  as  the  meanings  are  arranged  in  alpha- 
betical order  opposite  the  signals  to  be  sent. 

The  flags  and  pennants  used  in  the  Navy  for  making  flag  sig- 
nals are  the  alphabet  flags  of  the  International  Code  flags, 
except  the  code  pennant  (see  Chart  10)  and  a  number  of  special 
flags  and  pennants  contained  in  Charts  11  and  12. 

While  the  alphabet  flags  of  the  Navy  Code  are  same  in  design 
as  those  of  the  International  Code,  they  have  no  connection 
whatever.  A  distinct  naval  feature  is  to  call  the  flags  by  name 
rather  than  by  letter,  the  name  applied  to  the  alphabet  flags  are 
able  for  A,  boy  for  B,  etc.,  same  as  the  conventional  signals  used 
for  telephoning  on  page  66. 

CALLS 

Each  ship  in  the  Navy  is  furnished  with  a  call,  which  is  a 
combination  of  two  letters  like  ZL,  PN,  or  AD. 

For  sake  of  convenience  the  first  letter  of  a  ship's  call  repre- 
sents the  group  to  which  that  ship  belongs  and  the  second  letter 
the  ship  of  that  particular  group. 

One  set  of  flags  is  used  for  the  group  and  another  for  the  ship. 


88 


GILBERT    BOY    ENGINEERING 


GlLl&tl 


Obloti 


ee, 


FIG.  27 


GILBERT    SIGNAL    ENGINEERING  89 

The  two-letter  call  of  each  ship  is  made  by  using  one  of  the 
call  flags  and  one  of  the  call  pennants.  (See  Chart  11.) 

In  order  to  furnish  calls  to  squadrons,  divisions,  etc.,  of  a  fleet 
additional  flags  are  used  for  indicator  flags  and  will  be  found  on 
Chart  12  under  the  title,  Squadron,  Division,  Torpedo  Flotilla 
and  Submarine  Flotilla. 

The  call  of  a  particular  ship  wanted  to  take  a  message  would 
be  made  (in  case  of  a  number  of  naval  ships  of  various  classes 
in  immediate  vicinity)  by  its  indicator  flag  with  call  letters 
hoisted  underneath. 

Where  a  general  call  or  message  is  to  be  given  to  all  ships 
within  signal  distance,  the  cornet  flag  is  hoisted  without  indi- 
vidual call  letters  and  all  ships  are  required  to  answer. 

All  naval  vessels  passing  at  sea  always  hoist  their  call  letters. 
The  answering  pennant  is  used  to  answer  all  flag  signals,  and 
is  hoisted  from  point  best  seen  (at  truck  or  either  side  of  the 
signal  yard)  and  is  kept  there  until  ship  signaling  hauls  down  the 
signal.  The  answering  pennant  is  also  used  as  a  divisional  point 
in  making  a  numeral  hoist. 

The  alphabet  flags  from  Q  to  Z  are  designated  as  numerals 
from  1  to  0  respectively  and  are  so  indicated  when  the  numeral 
flag  precedes  them  on  a  hoist. 

The  repeaters  1st,  2d  and  3d  serve  to  reproduce  numeral 
hoisted  above  them.  The  first  repeater  would  act  as  a  repeater 
for  the  first  flag,  2d  repeater  for  second  and  so  on.  For  example, 
the  numeral  232  would  be  hoisted  using  the  numeral  flag  fol- 
lowed by  R(2),  S(3)  and  first  repeater. 

The  numeral  2222  would  be  hoisted  R(2)  1st,  2d,  and.  3d  re- 
peaters. 

The  Preparatory  Flag  (L)  means  prepare  to  execute  signal 
shown.  It  is  also  used  as  a  time  signal  by  the  flagship  or 
senior  ship  present,  in  which  case  it  is  hoisted  at  6:55  A.  M. 
and  hauled  down  promptly  at  7  A.  M.  It  also  indicates  that  the 


90  GILBERT    BOY    ENGINEERING 

uniform  of  crew  is  same  as  yesterday.  When  hoisted  at  7 : 45 
A.  M.  over  a  numeral  it  indicates  the  size  of  the  ensign  (colors) 
ships  are  to  hoist  at  8  A.  M.  It  is  hauled  down  at  8  A.  M.  and  all 
ships  then  hoist  the  national  colors. 

The  Interrogatory  Flag  (O)  hoisted  over  a  signal  changes  its 
meaning  into  the  interrogatory  form. 

The  Affirmative  Flag  (P)  when  hoisted  in  answer  to  a  signal 
means  yes,  or  permission  granted. 

The  Negative  Flag  (K)  when  hoisted  in  answer  to  a  signal 
means  no,  or  request  not  granted. 

The  Annulling  Flag  (N)  annuls  all  signals  at  time  display 
on  the  same  mast,  hoisted  alone  it  annuls  a  previous  signal 
which  has  just  been  made. 

The  Quarantine  Flag  (Q)  hoisted  at  foremast  truck  indicates 
ship  is  under  quarantine  or  has  an  infectious  disease  aboard. 

The  Guard  and  Guide  Flag,  when  hoisted  at  fore  truck  in  port 
between  sunrise  and  sunset,  indicates  that  that  ship  is  charged 
with  the  guard  duty  for  that  day  (a  red  truck  light  is  used  at 
night  at  foremast). 

When  hoisted  by  a  ship  under  way  it  indicates  that  that  ship 
is  to  guide  the  formation. 

The  guard  flag  is  displayed  on  all  the  small  boats  belonging 
to  the  ship  doing  guard  duty.  The  guard  flag,  however,  is  not  dis- 
played in  any  way  by  a  flagship  if  they  are  performing  that  duty. 

The  Convoy  and  Position  Pennant  is  worn  at  the  foretruck  of 
all  ships  on  convoy  duty;  in  formation,  when  hoisted  at  dip  it 
signifies  "I  am  temporarily  out  of  position/' 

The  Danger  and  Designating  Flag  hoisted  alone  means 
danger  ahead;  a  compass  signal  under  it  signifies  the  direction 
from  which  danger  is  expected. 

The  Dispatch  and  Breakdown  Flag  (I)  wHen  worn  at  main 
truck  indicates  that  that  ship  is  on  dispatch  duty;  in  fleet  for- 
mation this  flag  is  always  kept  rounded  up  ready  to  "break"  at 


GILBERT    SIGNAL    ENGINEERING 91 

foretruck  and  when  "broke,"  it  signifies  a  breakdown  of  ships 
machinery  or  the  steering  gear.  In  case  of  a  man  overboard  it  is 
"broken"  and  lowered  at  dip. 

The  General  and  Boat  Recall  Flag.  Hoisted  alone  this  flag 
calls  all  the  small  boats  back  to  their  respective  ship  at  once. 
When  hoisted  under  a  number  it  recalls  only  that  boat  or  boats 
having  these  numbers.  At  night  small  boats  are  recalled  by 
the  display  of  I  followed  by  boat  numbers  and  the  call  letters  of 
ship  signaling. 

The  Powder  and  Firing  Flag  (B)  is  displayed  at  the  foremast 
of  all  naval  vessels  engaged  in  taking  on  board  explosives,  such 
as  loaded  shells,  fuel  oil  or  gasoline. 

The  Meal,  Full  Speed  and  Flag  Officer  Leaving  Pennant, 
when  hoisted  singly  at  the  port  yardarm  by  a  ship  at  anchor, 
signifies  that  crew  is  at  meal ;  if  hoisted  at  sea  on  same  yardarm 
with  the  speed  cone,  it  means  one  knot  faster  than  standard 
speed;  alone  with  speed  cone  it  denotes  full  speed;  and  when 
hoisted  under  the  flag  of  any  flag  officer  it  conveys  the  fact  that 
that  officer  is  leaving  the  ship. 

The  Battle  Efficiency  Pennant  is  shown  at  the  foremast  (when 
ship  is  at  anchor)  of  ship  or  ships  which  are  authorized  to  fly 
same.  The  Battle  Efficiency  Pennant  is  awarded  each  year  by 
the  Navy  to  one  ship  in  each  of  the  battleship,  submarine  and 
torpedo  boat  class  for  excelling  in  gunnery  and  engineering  for 
that  particular  year. 

The  Church  Pennant  is  hoisted  over  the  ensign  while  divine 
services  are  being  held,  it  is  the  only  flag  ever  hoisted  over  the 
ensign  for  any  reason  whatsoever. 

The  Red  Cross  Flag  is  an  International  flag  flown  by  all  hos- 
pital ships,  their  small  boats  and  also  flown  at  Naval  Field  Hos- 
pitals. The  flag  is  flown  at  the  bowstaff  on  ships. 

The  Submarine  Warning  Flag  is  hoisted  and  flown  by  any 
vessel  or  small  boat  acting  as  a  mother  ship  or  fender  to  sub' 


92  GILBERT    BOY    ENGINEERING 

marines,   and   it   signifies   that   submarines   are   submerged   or 
operating  in  that  vicinity. 

U.  S.  NAVAL  FLAG  ETIQUETTE 

Every  ship  in  the  U.  S.  Navy  carries  a  complete  set  of  the 
various  national  ensigns  of  other  countries.  Some  nations  have 
two  ensigns,  each  different  in  design,  one  for  men-of-war  and 
another  for  merchant  vessels.  In  the  case  of  the  United  States 
government  the  national  colors  are  alike  for  both  naval  and 
merchant  ships. 

The  national  ensigns  of  foreign  countries  are  flown  from  the 
main  mast  of  U.  S.  Naval  vessels  on  occasions  such  as  a  visit 
irom  the  head  of  a  foreign  government  or  any  other  high  officials, 
either  diplomatic,  military  or  naval.  In  American  or  foreign 
waters,  on  occasion  of  such  a  visit,  the  national  ensign  of  the 
country  the  official  represents  is  made  up  and  "broke"  at  main 
mast  as  the  visitor  or  visitors  step  aboard.  At  time  flag  is 
broken  the  saluting  battery  fires  the  proper  salute  that  the 
visitor  is  entitled  to. 

U.  S.  Naval  ships  upon  entering  a  foreign  port  always  "break" 
the  national  ensign  of  the  nation  visited  and  fire  a  salute  of 
twenty-one  guns.  The  salute  is  answered  by  the  highest  official 
present  from  either  a  naval  vessel  or  a  military  shore  station  or 
fort. 

U.  S.  Naval  ships  passing  other  men-of-war  or  merchant  ships 
at  sea  always  dip  the  colors  in  answer  to  the  same  courtesies. 
It  is  customary  for  merchant  ships  of  either  U.  S.  or  foreign 
countries  to  dip  colors  to  the  men-of-war  first.  However,  in  case 
of  naval  vessels  meeting,  the  junior  officer  always  dips  first  to 
his  senior.  No  salutes  are  fired  as  a  rule  to  naval  officers  of  a 
rank  lower  than  a  flag  officer,  which  in  the  U.  S.  Navy  is  a 
Rear  Admiral  or  above  in  rank,  except  where  an  officer  lower 
in  rank  may  be  acting  in  that  capacity. 


GILBERT    SIGNAL    ENGINEERING  93 

TIME  FOR  FLYING  COLORS 

The  time  for  flying  of  the  national  ensign  on  naval  ships  is 
given  by  the  senior  officer  present.  The  size  of  colors  to  be 
used  is  also  designated  by  signal.  As  a  general  rule  the  colors 
are  hoisted  at  8  A.  M.  in  port  and  at  the  flagstaff  at  stern  of 
ship  with  the  proper  ceremonies.  At  sea  the  colors  are  hoisted  at 
the  gaff  (small  spar  projecting  from  the  main  mast).  The  colors 
are  lowered  at  sunset  with  the  same  ceremonies,  but  at  sea  the 
colors  are  usually  replaced  after  being  lowered  by  a  smaller 
ensign  which  flies  all  night,  as  do  certain  other  special  designator 
and  personal  flags.  It  is  not  customary  to  signal  by  means  of 
flags  before  morning  or  after  evening  colors. 

The  Union  Jack  is  hoisted  in  port  only  and  at  jackstaff  in  bow. 
It  is  hoisted  at  morning  colors  and  lowered  at  evening  colors. 
The  Union  Jack  hoisted  at  fore  signal  yard  indicates  there  is  a 
general  court  martial  or  court  of  inquiry  being  held  aboard. 
When  hoisted  for  such  purposes  a  gun  is  fired.  The  Union  Jack 
hoisted  at  foremast  truck  calls  a  pilot  aboard. 

PERSONAL  FLAGS 

Chart  13  gives  the  personal  flags  of  the  higher  officers  in  U.  S. 
Navy,  along  with  special  distinguishing  flags  of  the  naval  militia 
and  yachts. 

The  President's  Consular  and  flags  of  Secretaries  of  the  Navy 
are  used  on  any  visit  to  a  naval  vessel  by  these  officials. 

The  personal  flags  of  Admiral,  Vice  Admiral  and  the  Rear 
Admirals  are  flown  at  the  main  mast  truck  of  their  respective 
flagships. 

The  Blue  Pennant  of  Senior  Officer  present  is  known  by  the 
ship  having  the  senior  officer  of  any  group  of  naval  vessels  in 
the  absence  of  a  flag  officer. 

All  naval  ships  in  commission  fly  the  commission  pennant  at 


94 GILBERT  BOY  ENGINEERING 

the  main  mast  truck.  This  pennant  really  acts  as  a  personal 
flag  of  the  commander  of  the  ship  and  in  case  of  a  flagship  it  is 
not  worn,  as  the  flag  officer's  personal  flag  signifies  that  that 
ship  is  in  commission. 

The  Naval  Militia  Distinguishing  Flag  is  worn  at  foremast 
truck  of  all  naval  vessels  loaned  by  the  Navy  department  to  a 
state  for  use  of  Naval  Militia  or  Naval  Reserves  when  such  ves- 
sels are  under  command  of  Naval  Militia  or  Reserve  Officers. 
The  Naval  Militia  Commission  Pennant  is  worn  at  main  mast 
truck  on  such  ships,  and  in  event  of  ship  having  a  flag  officer 
aboard  his  personal  flag  is  flown  instead  at  main  truck.  The 
rank  of  Commodore  is  the  highest  in  Naval  Militia. 

YACHT  FLAGS 

.* 

It  is  required  by  law  that  all  pleasure  yachts  and  boats  of 
more  than  15  tons  display  the  yacht  ensign.  This  you  will  note 
by  referring  to  Chart  12  is  different  in  design  from  the  national 
ensign  and  serves  to  signify  when  worn  that  that  particular  ship 
is  a  pleasure  boat. 

Yachts  fly  all  personal  flags  in  a  similar  way  as  used  in  Navy. 
For  signaling,  they  use  all  navy  methods  except  Navy  Flag  Code. 
The  substitute  being  the  International  Flag  Code  for  flag  hoist 
signals. 


Chapter  X 
MISCELLANEOUS  SIGNALS 

INTERNATIONAL  LIFE  SAVING  SIGNALS 

1.  Upon  the  discovery  of  a  wreck  at  night,  the  life-saving 
shore  station  burns  a  red  light  or  sends  up  a  red  rocket  to  sig- 
nify "You  are  seen,"  assistance  will  be  given  soon  as  possible. 

2.  A  red  flag  waved  on  shore  by  day  or  a  red  light  or  red 
rocket  by  night  means  "Haul  away." 

3.  A  white  flag  waved  on  shore  by  day  or  a  white' light  waved 
slowly  or  white  rocket  by  night  means  "Slack  away." 

4.  Two  flags — a  white  and  a  red — waved  at  same  time  on 
shore  by  day,  or  two  lights — a  white  and  red — swung  slowly  or 
a  blue  light  burned  by  night  signifies  "Do  not  attempt  to  land  in 
your  own  boats,  it  is  impossible." 

5.  A  man  on  shore  beckoning  by  day  or  two  torches  burning 
closely  together  by  night  will  signify  "This  is  the  best  place  to 
land/' 

SIGNALS  FOR  A  PILOT 

Any  of  the  following  when  displayed  from  a  ship  will  call  a 
pilot : 

1.  The  Jack,  hoisted  at  the  foremast. 

2.  The  International  Code  pilot  signal  indicated  by  the  alpha- 
bet letters  P  T. 

3.  The  International  Code  flag  S  displayed  alone  or  with  code 
pennant  over  it. 

4.  The  Distant  Signal,  with  cone  pointed  upward,  having 
above  it  two  balls  or  oval  shapes. 

(95) 


96  GILBERT    BOY    ENGINEERING 

5c  At  night,  a  blue  light  burned  at  intervals  of  about  fifteen 
minutes  or  a  bright  white  light  flashed  at  short  intervals  just 
above  the  deck. 

6.  To  signal  for  a  tow  boat  place  the  National  Ensign  in 
main  rigging  just  above  the  decks  at  intervals  of  one  minute 
at  a  time. 

INTERNATIONAL  DISTRESS  SIGNALS,  FOR  DAY 

1.  A  gun  or  other  explosives  fired  at  intervals  of  one  minute. 

2.  The  International  Code  letters  N  C. 

3.  Fog  Signal  apparatus  sounded  steady. 

4.  The  Distant  Signal  consisting  of  a  cone  pointed  upward, 
having  either  above  or  below  it  a  ball  or  oval  shape. 

INTERNATIONAL  DISTRESS  SIGNALS,  FOR  NIGHT 

1.  Gun  or  other  shot  fired  every  minute. 

2.  Flames  of  a  burning  tar  or  oil  barrel. 

3.  Rockets  or  shells  throwing  stars  any  color  at  short  inter- 
vals. 

4.  Foghorn  sounded  steady. 

The  United  States  Weather  Bureau  is  operated  under  the 
Department  of  Agriculture.  The  Bureau  has  many  stations 
throughout  the  country  as  well  as  142  stations  on  the  Atlantic 
and  Gulf  Coasts  and  46  stations  on  the  Pacific  Coast. 

Weather  predictions  are  given  out  from  these  stations  to  all 
the  newspapers,  and  bulletins  are  furnished  to  all  Federal  build- 
ings for  posting. 

The  inland  stations  have  telegraphic  connections  with  the 
coast  stations  and  inform  them  of  the  approach  of  severe  storms. 
The  coast  stations  in  turn  notify  mariners  by  means  of  flag 
signals  and  radio. 


GILBERT    SIGNAL    ENGINEERING 97 

All  the  civilized  nations  of  the  world  maintain  a  similar  sys- 
tem in  which  their  coast  stations  give  information  to  ships. 

The  Weather  Signal  flags  may  be  seen  by  turning  to  colored 
Chart  14;  at  bottom  of  same  chart  are  storm  and  -wind  signal 
flags,  along  with  night  lantern  signals. 

The  Weather  and  Storm  Signal  flags  when  displayed  on  a 
flag  pole  are  arranged  to  read  from  top  down.  When  single 
hoists  of  several  flags  are  made  on  a  signal  yard  a  small  streamer 
is  used  to  indicate  the  point  from  which  signals  are  to  be  read. 

Temperature  forecasts  signals  are  made  by  using  the  weather 
flags,  five  in  number — four  square  flags  and  one  pennant. 

The  flags  are  displayed  at  weather  bureau  stations  as  fol- 
lows, and  indicate  weather  predictions  for  next  twenty-four 
hours,  commencing  at  8  P.  M.  of  day  the  signals  are  made : 

1.  Square  white  flag  indicates  clear  or  fair  weather. 

2.  Square  blue  flag  indicates  rain  or  snow. 

3.  Square  flag  white  on  upper  half  and  blue  on  lower  half  in- 
dicates local  rains  or  showers  will  occur  and  that  rainfall  will 
not  be  general. 

4.  Square  white  flag  with  black  square  center  indicates  the 
approach  of  a  sudden  and  decided  drop  in  temperature — a  cold 
wave. 

5.  Black  pennant  is  used  to  refer  to  temperature  and  has 
no  meaning  hoisted  alone.     In  no  case  is  it  ever  hoisted  with 
the  square  white  flag  with  black  center.     (Cold  wave  flag.) 

The  black  pennant  hoisted  above  square  white  flag,  blue  flag 
and  white  and  blue  flag  indicates  warmer  weather  along  with 
the  regular  indication  that  that  flag  stands  for.  When  hoisted 
below  any  of  these  flags  it  means  colder  weather. 

Storm  and  Wind  Signals.    The  warnings  adopted  by  the  U.  S. 
Weather  Biireau  to  announce  the  approach  of  wind  storms  are 
as  follows :     (See  bottom  of  colored  Chart  14.) 
L  —  7 


98  GILBERT    BOY    ENGINEERING        

The  Small  Craft  Warning.  A  red  pennant  indicates  that 
moderately  strong  winds  that  will  interfere  with  the  safe  opera- 
tion of  small  craft  are  expected.  No  night  display  of  small  craft 
warnings  is  made. 

The  Northeast  Storm  Warning.  A  red  pennant  above  a 
square  red  flag  with  black  center  displayed  by  day  or  two  red 
lanterns,  one  above  the  other,  displayed  by  night  indicates  the 
approach  of  a  storm  of  marked  violence  with  winds  beginning 
from  the  northeast. 

The  Southeast  Storm  Warning.  A  red  pennant  below  a 
square  red  flag  with  black  center  displayed  by  day  or  one  red 
lantern  displayed  by  night  indicates  the  approach  of  a  storm 
of  marked  violence  with  winds  beginning  from  the  southeast. 

The  Southwest  Storm  Warning.  A  white  pennant  below  a 
square  red  flag  with  black  center  displayed  by  day  or  a  white 
lantern  below  a  red  lantern  displayed  by  night  indicates  the 
approach  of  a  storm  of  marked  violence  with  winds  beginning 
from  the  southwest. 

The  Northwest  Storm  Warning.  A  white  pennant  above  a 
square  red  flag  with  black  center  displayed  by  day  or  a  white 
lantern  above  a  red  lantern  displayed  by  night  indicates  the 
approach  of  a  storm  of  marked  violence  with  winds  beginning 
from  the  northwest. 

Hurricane  or  Whole  Gale  Warning.  Two  square  red  flags 
with  black  centers,  one  above  the  other,  displayed  by  day  or  two 
red  lanterns,  with  a  white  lantern  between,  displayed  by  night 
indicates  the  approach  of  a  tropical  hurricane,  or  one  of  the  ex- 
tremely severe  and  dangerous  storms  which  occasionally  move 
across  the  Great  Lakes  and  Atlantic  Coast, 


Chapter  XI 
HOW  TO  MAKE  SIGNAL  APPARATUS 

Flag  Making.  The  most  suitable  material  for  flag  making  is 
either  galatea  or  calico.  The  color  and  dimensions  of  the  cloth 
are  dependent  upon  type  of  flag  wanted  and  the  size. 

The  tools  necessary  are  a  straight-edged  yardstick  or  ruler, 
a  soft  pencil  or  chalk  for  marking  off  the  cloth,  an  old  safety 
razor  blade  or  a  pair  of  scissors  for  cutting  and  needle  and 
thread  for  stitching  flag  together.  You  can  get  your  mother  or 
sister  to  do  all  sewing  required  on  the  sewing  machine. 

Making  Wigwag  Flags  The  standard  dimensions  of  the  wig- 
wag flags  used  by  the  Signal  Corps  are  the  3-foot,  9-inch  square 
flag  with  12-inch  square  center  and  the  2-foot  square  flag  with 
8-inch  square  center. 

The  2-foot  size  flag  is  large  enough  for  most  signaling  and 
it  will  be  best  for  you  to  adopt  this  size  or  possibly  smaller  as 
the  larger  type  is  only  useful  in  case  of  extreme  distances.  The 
12-foot  staff  necessary  to  carry  a  flag  this  large  is  very  hard  to 
handle. 

The  2-foot  wigwag  flag  needs  a  staff  5j4  feet  in  length.  If 
flag  is  made  smaller  than  this  the  staff  can  be  made  shorter 
and  the  center  square  can  be  cut  down  to  a  proportionate  size. 

The  color  combinations  for  wigwag  flags  are  turkey  red  and 
white,  or  scarlet  and  yellow.  Blue  and  white  is  sometimes 
used  and  is  very  good,  but  red  and  white  is  the  best. 

Flags  can  be  made  up  using  any  of  above  combinations,  al- 
ternating the  colors  of  the  body  of  the  flag  and  center  for  use 
against  different  backgrounds. 

(99) 


100 


GILBERT    BOY    ENGINEERING 


FLAG  MAKING 


CHART     16 


GILBERT    SIGNAL    ENGINEERING  101 

No.  1  of  Chart  16  shows  the  proper  way  to  lay  out  a  wig- 
wag flag.  The  cloth  can  be  tacked  to  any  flat  surface  and, 
with  a  ruler  and  pencil,  a  square  can  be  marked  off  the  exact 
size  wanted.  Lines  can  then  be  drawn  from  corner  to  corner 
as  shown.  This  serves  to  he*lp;  get  ,the  square  >  in  the  exact 
center.  The  cloth  can  then  be  cui  ai'burtd  the  dotted  lines,  which 
should  be  about  J4  or  ^  itich.{rQm;£<ige;  pf  'flag./, This  gives 
enough  margin  for  hemming*/  *'T/t?e* next* Step' is  to*  turn  down 
the  edges  of  flag  and  pin.  A  selvedged  edge  can  then  be  made 
by  hemming  on  a  sewing  machine  or  stitching  by  hand.  After 
this  is  done  another  small  piece  of  cloth  of  opposite  color  is 
marked  off  as  pictured  in  No.  2.  The  size  of  square  being 
same  as  the  square  in  center  of  flag.  The  smaller  piece  of 
cloth  is  then  cut  around  on  the  dotted  lines  and  hemmed  around 
the  edge,  after  which  it  is  placed  over  the  square  of  the  larger 
piece  of  cloth  and  sewed  on.  Be  careful  to  stitch  as  close  to 
edge  as  possible.  After  this  the  flag  can  be  turned  over  and 
cut  out  on  inside  of  stitching  with  a  pair  of  scissors.  This 
brings  the  square  through  and  makes  flag  the  same  on  both 
sides.  The  flag  is  now  complete  except  for  a  staff  and  the  fasten- 
ings necessary. 

Ties  can  be  sewed  on  flag  as  shown  in  No.  3,  using  flat 
binding  tape.  Three  ties  will  be  enough — one  in  center  and  one 
at  each  end,  as  seen  in  No.  4  on  the  completed  flag.  For  a 
staff  a  bamboo  fishing  pole  can  be  used  or  any  round  pole  of  24 
to  1  inch  in  diameter. 

No.  5  suggests  several  ways  of  making  a  jointed  pole  if 
one  is  wanted  to  make  flag  staff  convenient  to  carry  on  a  hike. 

THE  WIGWAG  DISC 

No.  6  suggests  a  disc  for  wigwagging.  The  disc  can  be 
either  cut  out  of  a  piece  of  tin  or  heavy  cardboard,  painted  in 
colors  black  and  white  or  red  and  white  and  then  tacked  to  a 


102  GILBERT    BOY    ENGINEERING 

slender  stick  or  pole.  This  piece  of  signal  apparatus  is  easily 
made  and  has  the  advantage  over  the  flag  on  a  windy  day  as 
flag  is  very  apt  to  foul  while  the  disc  is  not  open  to  this  objection. 

SEMAPHORE  FLAG  MAKING 

Semaphore  flags  can  be  made  exactly  like  wigwag  flags  except 
for  size,  which  v?rV  -from  tl?eN  1Q  and  15-inch  sizes  used  in 
Navy  to  24-inch  size  which  is  the  largest  used  by  the  Army. 

For  all  around  semaphore  signaling  the  12  to  18-inch  size  will 
be  found  most  adaptable.  The  flags  are  always  made  square  in 
shape  and  usually  of  a  design  like  the  wigwag  flags,  with  square 
center  or  the  diagonal  type  illustrated.  (No.  8.) 

No.  7  shows  the  way  to  mark  off  cloth  for  cutting  out  the 
diagonal  flag. 

The  ties  for  fastening  flag  to  stick  can  be  made  the  same  way 
as  in  the  case  of  the  wigwag,  but  need  not  be  as  strong.  The 
darkest  portion  of  flag  goes  next  to  stick  and  the  stick  should 
be  only  long  enough  to  allow  a  hand  hold  below  the  flag.  The 
stick  can  be  notched  to  keep  ties  in  place ;  or  another  way  which 
makes  a  neat  effect  is  to  make  eyelets  as  shown  in  No.  9. 
This  is  done  by  shaping  the  eyelets  out  of  a  piece  of  copper 
wire,  flattening  the  ends  and  binding  them  to  the  stick  with 
fine  wire  or  heavy  thread,  after  which  a  coat  of  varnish,  if  added, 
will  put  on  the  finished  appearance. 

HOW  TO  MAKE  A  FIELD  BUZZER  OUTFIT 

The  field  buzzer  is  an  instrument  used  by  Boy  Scouts  and 
armies  for  sending  and  receiving  signals  between  temporary 
stations.  It  is  strictly  a  portable  instrument.  The  one  used  by 
the  United  States  Army  can  be  used  for  many  kinds  of  sig- 
naling. It  will  work  as  a  telephone  or  as  a  telegraph.  Of  course 
it  is  used  as  a  telephone  whenever  possible ;  but  when  the  con- 
necting lines  are  broken,  it  is  possible  to  use  the  sets  as  tele- 


GILBERT    SIGNAL    ENGINEERING 103 

graph  stations,  and  messages  are  sent  and  received  in  the  form 
of  a  high  pitched  hum  very  much  like  that  of  a  radio  signal. 

In  actual  field  use,  these  messages  have  been  sent  and  re- 
ceived when  the  lines  were  cut  off  but  both  ends  of  the  line 
slightly  grounded.  It  is  not  hard  to  make  an  instrument  similar 
to  the  United  States  Service  Buzzer  which  will  give  the  Gilbert 
Signal  Engineers  lots  of  sport  as  well  as  practice  in  telephone 
and  telegraph  work.  This  amateur  set  will  not,  of  course,  be 
so  elaborate  as  the  army  set,  because  the  latter  is  made  for  use 
in  all  sorts  of  weather,  in  all  sorts  of  places. 

But  for  practice  work,  the  little  sets  described  below  will 
serve  you  just  as  well  and  will  be  cheaper  and  easier  to  build. 

TELEGRAPH  BUZZER 

This  instrument  can  not  be  used  as  a  telephone  set,  but  can 
send  and  receive  Morse  and  Continental  Code  telegraph  mes- 
sages. 

SERVICE  BUZZER 
Parts  Required 

1.  Panel — This  should  be  about  l/%  of  an  inch  thick  and  can 
be  made  of  hard  black  rubber,  black  fibre,  or  even  thin  wood 
painted  or  stained  to  make  it  look  well.     This  panel  should  be 
6  inches  long  and  Zy2  inches  wide. 

2.  Battery — Purchase  five  flash  light  batteries  and  connect 
them  in  series.     The  batteries  used  in  the  set  described  here 
measure  1^  wide,  11/16  inches  thick  and  2%  inches  long.    But 
batteries  of  other  size  can  be  used  if  necessary,  and  the  only 
change  in  the  set  required  will  be  in  the  wooden  box  enclosing 
the  set  and  in  the  size  of  the  panel. 

3.  Key  or  Button — For  this  set  an  ordinary  doorbell  push 
button  will  do  very  well. 

4.  Telephone   Receiver— Purchase  a   75   ohm   telephone  re- 
ceiver of  the  watch  case  type. 


104 


GILBERT    BOY    ENGINEERING 


To  OTMBR  5wnon 


PANEL  SHOWING  COMPLETE  ASSEMBLY 
CONNECTING   WIRES  SHOWN   DOTTED 


FIG.  28 


GILBERT    SIGNAL    ENGINEERING  105 

5.  Vibrator  and  Vibrator  Coil — You  can  buy  a  buzzer  such, 
as  is  used  for  sending  practice  in  wireless  telegraphy,  or,  if  you 
prefer  to  make  one  yourself,  you  will  find  the  following  instruc- 
tion helpful. 

Cut  two  cardboard  or  fibre  discs;  these  should  be  about  24 
inches  in  diameter.  Put  a  hole  through  the  center  3/16  inches 
in  diameter  and  two  small  holes  for  the  wire  to  pass  through 
as  near  the  edge  as  possible  and  on  opposite  side  of  the  large 
center  hole.  These  small  holes  can  be  made  with  a  small  nail 
or  an  awl.  (See  Figure  29.) 

Make  two  supports  for  the  buzzer,  using  1/16  inch  steel  and  a 
vibrator  of  springy  steel  about  1/64  of  an  inch  thick. 

Place  an  8-32  round  head  steel  machine  screw  \l/%  inches  long 
through  one  of  the  supports  and  washers,  holding  the  latter 
tightly  against  the  screw  head.  Wrap  six  or  seven  layers  of 
writing  paper  around  the  body  of  the  screw.  Make  the  width 
of  this  paper  24  of  an  inch.  Place  the  other  washer  on  the 
screw  and  tighten  it  against  the  end  of  the  paper  wrapper,  by 
means  of  a  steel  nut.  Wind  over  the  paper  25  feet  of  No.  24 
B&S  Gauge  copper  wire  insulated  either  with  enamel  or  cotton. 

Start  this  winding  by  pushing  a  beginning  of  the  wire  through 
one  of  the  small  holes  in  the  end  washer,  leaving  about  2l/2 
inches  of  wire  sticking  through  the  hole  for  a  connecting  lead. 
When  the  coil  is  complete,  stick  the  end  through  one  of  the 
other  small  holes  and  your  magnet  is  complete. 

Next  you  will  need  a  support  for  the  adjusting  screw,  which 
should  be  of  brass  8-32  and  about  l/2  inch  long.  This  is  locked 
in  place  by  an  adjusting  nut. 

6.  Box — This  should  be  a  well-made  box  with  a  hinged  cover 
and  clasp.     (See  Figure  30.)    Make  the  inside  dimensions  of  the 
box  6  inches  long,  Zl/2  inches  wide  and  2  inches  deep.    The  cover 
should  be  6  inches  by  Zl/2  inches  by  1  inch  deep.    If  you  plan  to 


106 


GILBERT    BOY    ENGINEERING 


V1NDIN6 


SUPPORT 


END  Disc. 


ADJUSTING 
SCREW  &  SUPPORT 


BUZZEFS  SIDE  &  TOP  VIEW 


FIG.  29 


GILBERT    SIGNAL    ENGINEERING 


107 


use  the  buzzer  on  hikes,  it  will  be  well  to  put  a  carrying  strap  of 
leather  or  webbing  on  the  box. 

The  batteries  should  be  held  in  place  by  end  blocks  of  wood 
and  also  by  the  two  brass  terminal  strips  shown  in  Figure  28. 
The  battery  terminals  should  be  placed  so  they  make  good  con- 
tact with  these  brass  strips  so  that  the  first  battery  on  the  right 


BOX  COMPLETE. 
FIG.  30 

has  the  outside  terminal  against  the  upper  strip,  the  next  will 
have  the  outside  terminal  against  the  lower  strip.  Alternate 
these  connections  until  all  the  batteries  are  in  place. 

Make  the  connections  as  shown  in  the  diagram  (Figure  28), 
fasten  the  panel  in  place,  attach  the  telephone  receiver  to  the 
binding  screw  and  the  instrument  is  ready  for  use.  It  will  be  a 
great  help  if  you  make  an  iron  pin  to  push  into  the  ground  for 
one  side  of  the  line  circuit.  The  other  side  should  be  a  copper 
wire  at  least  as  large  as  No.  24  B&S  Gauge. 

BUZZER  AND  PHONE  COMBINED 

If  in  the  above  instrument  we  had  used  a  telephone  receiver 
connected,  as  shown  in  the  next  diagram  (Figure  31),  with  this 


108 


GILBERT    BOY    ENGINEERING 


circuit  when  the  key  is  closed,  a  single  click  would  have  been 
heard  in  the  receiver. 

If  the  key  is  held  down,  no  further  sound  will  be  heard  unless 
some  one  speaks  into  the  transmitter.  The  set  will  then  act  as 
a  telephone.  We  will  not  take  the  time  here  to  explain  the 
telephone  theory.  It  requires  a  book  by  itself. 


FIG.  31 

Now  we  can  combine  the  telegraph  and  telephone  instruments 
in  one  by  the  addition  of  a  second  push  button  or  key  and  a 
transmitter.  Study  the  connection  diagrams  shown  (Figures  32 
and  33)  and  you  will  have  very  little  trouble  in  understanding 
how  to  build  this  set. 

When  you  wish  to  use  this  outfit  as  a  telephone,  you  press 
Key  No.  2,  holding  it  closed.  A  current  will  then  flow  from  the 
+  side  of  the  battery  to  the  ground,  from  the  ground  it  will 
pass  through  the  grounded  side  of  the  listening  station,  around 
the  buzzer  winding,  through  the  listening  station  receiver  to 
the  line  back  to  the  sending  station,  through  the  sending  station 
receiver  to  the  telephone  transmitter,  from  the  transmitter  to 
Key  No.  2  and  from  Key  No.  2  to  the  battery,  thus  completing 


GILBERT    SIGNAL    ENGINEERING 


109 


UPPER 


TRAM5MJTTEH 


Z3D 


•I'b 

T^ 

OATTERV 

LINE 

GROUMD 

FIG.  32 

the  Circuit.  Note  the  whole  battery  is  not  used  for  this  circuit 
but  only  two  batteries  are  connected  by  a  tap  for  the  telephone 
use. 

When  the  speaker  at  the  sending  station  talks  into  the  trans- 
mitter, his  voice  sets  the  little  granules  of  carbon  in  motion,  thus 
varying  the  resistance  of  the  circuit.  This  causes  the  current  to 


KEY  OR.  BUTTON  No  I 


110 GILBERT  BOY  ENGINEERING 

fluctuate,  causing  the  magnet  in  the  receiver  to  vibrate  the  dia- 
phragm for  every  tone  the  sender  utters.  This  is  heard  as  a 
telephone  message  by  the  listener  at  the  receiving  end. 

To  use  the  telegraph  circuit,  Key  No.  1  is  pressed.  When  it 
closes  the  circuit,  the  current  flows  from  the  positive  side  of  the 
battery  to  the  buzzer  coil,  to  the  vibrator.  From  the  vibrator 
it  passes  to  the  brass  contact  screw,  but  at  this  point  the  circuit 
is  rapidly  opened  and  closed  due  to  the  action  of  the  magnet  and 
vibrator.  From  the  contact  screw,  the  current  passes  to  the 
Key  No.  1,  from  the  key  back  to  the  negative  side  of  the  entire 
battery. 

But  in  addition  to  this  there  is  also  a  current  flowing  from  the 
ground  to  the  receiving  station  ground,  through  the  receiving 
station  buzzer  coil,  from  the  coil  to  the  receiving  station  tele- 
phone receiver  where  a  high  pitched  hum  is  heard,  from  the  re- 
ceiver to  the  line  back  to  the  line  side  of  the  sending  instrument 
receiver  to  sending  station  buzzer  coil  and  back  to  the  ground. 

When  the  sending  station  buzzer  starts  vibrating,  it  sets  up 
a  pulsating  current  in  the  second  circuit  which  can  be  heard  as 
dots  and  dashes  in  the  receiving  station  receiver  when  the 
sending  key  is  operated  properly. 

With  two  of  these  instruments  it  is  possible  for  two  boys  to 
have  lots  of  fun  and,  at  the  same  time,  learn  many  of  the  ele- 
ments of  electric  signaling. 

In  the  Army  Service  Buzzer  there  are  other  parts  such  as 
the  condenser,  so  that  the  soldiers  can  attach  the  instruments 
to  any  telegraph  lines  in  the  country  where  they  happen  to 
be.  This  allows  them  to  operate  without  interfering  with  the 
regular  telegraph  work  of  the  line. 

But  these  things  make  the  set  a  little  more  complicated  and 
are  not  necessary  for  the  average  boy,  so  we  will  not  describe 
them. 


GILBERT    SIGNAL    ENGINEERING m 

HOW  TO  MAKE  A  HELIOGRAPH 

Before  trying  to  make  the  heliograph  outfit  illustrated  on 
Chart  17  read  over  carefully  the  theory  of  heliographing  in 
Chapter  V,  page  50,  and  with  these  principles  thoroughly  fixed 
in  your  mind  the  making  and  operating  of  the  heliograph  will  be 
very  easy. 

To  make  heliograph  as  shown  the  station  mirror  and  the 
two  diaphragms  L(Nos.  2  and  3)  are  supported  on  a  tripod, 
made  by  using  a  2x4  or  4x4  inch  upright.  This  can  be  sharpened 
and  driven  in  the  ground  about  1J4  or  2  feet,  after  which  a 
2x4  inch  piece  6j4  feet  long  can  be  fastened  through  the  flat 
side  at  the  center  to  the  post  by  a  large  screw.  This  will  allow 
the  instrument  to  turn  so  as  to  face  in  any  direction  desired. 

The  station  mirror  can  be  made  as  pictured  by  using  a  plate 
glass  mirror  4  inches  square.  The  mirror  is  set  in  a  frame  made 
of  picture  moulding.  The  framed  mirror  is  then  mounted  in  a 
U-shaped  easel.  The  easel  can  be  made  out  of  1x1  inch  lumber 
and  strengthened  by  using  small  angle  irons  at  corners.  (These 
can  be  purchased  at  any  hardware  store.)  The  mirror  frame  can 
be  suspended  in  the  easel  by  attaching  it  to  large  size  nails  in- 
serted in  the  holes  that  have  been  drilled  through  the  center  of 
the  frame  and  the  upright  ends  of  the  easel.  A  spring  arrange- 
ment is  then  placed  on  each  side  of  the  mirror  frame  between 
the  uprights  of  the  easel.  This  can  be  worked  out  so  that  the 
mirror  will  set  rigid  at  any  angle. 

The  easel  is  bolted  to  one  end  of  the  tripod,  using  several 
washers  on  the  bolt,  between  the  2x4  and  easel.  The  station 
mirror  can  then  be  turned  to  right  or  left. 

The  diaphragms,  Nos.  2  and  3,  can  be  made  out  of  tin, 
cardboard  or  light  wood.  Both  of  them  can  be  made  the  same 
size,  about  8x12  inches,  with  the  8-inch  side  at  top.  The  dia- 
phragms are  cut  out  so  as  to  slide  on  the  2x4  piece.  They  are 
balanced  and  supported  by  a  piece  of  wood  to  which  several 


112 


GILBERT  BOY  ENGINEERING 


HOW    TO   MAKE   A  HELIOGRAPH 


STA.  MIRROR 
1 


V 


XI 


CHART      17 


GILBERT  SIGNAL  ENGINEERING 113 

blocks  are  nailed  on  each  side  as  shown.  The  diaphragm  is  of 
course  tacked  to  the  wood  supports;  this  allows  the  completed 
diaphragm  to  slide  on  the  2x4  piece  of  the  tripod. 

The  diaphragm  shown  in  No.  2  has  a  square  hole  3x3  inches 
at  center,  with  cross  wires.  That  shown  in  No.  3  has  a  square 
hole  2x2  inches,  with  cross  wires  or  thread. 

In  making  the  diaphragms  a  great  deal  of  care  must  be  given 
to  obtaining  the  right  size  hole  in  each  and  also  that  in  the 
center  of  the  station  mirror.  (Make  the  hole  in  the  exact  center 
of  station  mirror  by  scratching  off  a  little  of  the  silver.)  The 
cross  wires  in  each  diaphragm  must  be  exactly  in  line. 

HOW  TO  OPERATE 

The  advantage  of  this  type  of  heliograph  over  the  open  mirror 
type  is  that  it  reduces  the  beam  of  light  down  to  a  direct  flash 
by  means  of  the  two  diaphragms.  The  result  of  which  is  shown 
on  Chart  17  by  the  dotted  line  which  represents  the  straight 
course  of  the  rays  coming  from  the  second  diaphragm  (No.  3). 

The  first  diaphragm  should  be  placed  about  1  foot  from  the 
station  and  the  second  diaphragm  (No.  3)  about  3l/2  to 
4j/2  feet  distant  from  the  first ;  as  both  slide  they  can  be  adjusted 
easily  to  the  proper  distance. 

By  lining  up  the  receiving  station  through  peep  hole  and  cross 
wires  of  both  of  the  diaphragms  and  the  station  mirror  angled 
so  as  to  catch  the  sun's  rays,  the  apparatus  is  ready  to  send  the 
message. 

The  flashes  can  be  intercepted  by  using  a  piece  of  tin  or  wood 
about  12x12  inches  square,  to  which  several  pieces  of  1x1  inch 
wood  can  be  nailed,  as  pictured  at  lower  right  hand  corner  of 
Chart  17.  This  gives  a  good  hand,  hold  and  perfect  control  of 
your  shutter. 
L  — 8 


114 GILBERT  BOY  ENGINEERING 

An  additional  mirror  will  be  necessary  should  the  sun  be  be- 
hind the  sender.  The  extra  mirror  can  be  held  by  another  boy  in 
this  case  so  as  to  deflect  the  sun's  rays  into  the  station  mirror. 

A  little  practice  will  be  necessary  to  get  accustomed  to  the 
adjustment  required  when  the  angle  which  the  sun's  rays  make 
with  the  mirror  changes  at  different  times  during  the  day.  When 
the  knack  of  arranging  the  mirror  is  acquired  you  will  have  no 
trouble  in  sending  a  message  up  to  twenty-five  miles,  if  that 
distance  is  required  with  this  outfit, 

HOW  TO  MAKE  A  SEMAPHORE  AND  BLINKER 

The  semaphore  at  center  of  Chart  18  needs  little  explanation 
as  it  is  simply  two  cross  arms  with  paddles  which  can  be  painted 
in  conspicuous  alternating  colors  so  as  to  be  readable  at  a 
distance. 

The  post  which  carries  the  semaphore  arms  can  be  any  height 
desired.  The  arms  to  which  paddles  are  nailed  should  be  made 
of  1x1  inch  light  pine  wood  and  the  paddles  about  j4  or  H  inches 
thick  by  2J^  feet  in  length  and  6  to  8  inches  in  width. 

The  semaphore  arms  are  bolted  or  nailed  below  the  other 
arms  so  as  to  fold  back  to  post  when  not  in  use.  This  extra 
arm  indicates  to  receiving  station  the  sender's  right  or  left. 

Messages  are  transmitted  by  pulling  the  semaphore  wings  up 
by  means  of  the  cord  to  a  position  at  right  angles  to  the  upright 
post  and  then  dropping  same  immediately  to  a  position  parallel 
to  and  in  back  of  the  post. 

The, right  wing  when  pulled  up  to  the  position  mentioned  will 
indicate  the  dot  of  the  General  Service  Code  and  the  left  wing 
will  indicate  the  dash.  The  end  of  word  can  be  indicated  by 
raising  both  arms  at  same  time  and  the  end  of  sentence  by 
swinging  the  arms  a  little. 


GILBERT  SIGNAL  ENGINEERING 


115 


MAKING  A  5EMAPHORE  ^BLINKER 


\ 


CHART     18 


116  GILBERT  BOY  ENGINEERING 

THE  BLINKERS 

Two  types  of  blinker  lights  for  sending  messages  by  General 
Service  Code  are  pictured  on  Chart  18. 

The  blinker  at  the  right  on  the  chart  is  made  with  a  lantern 
and  operated  by  a  cord  passing  over  two  small  pulleys.  The 
lantern  is  so  suspended  as  to  make  it  possible  to  drop  it  in  a 
bucket,  which  of  course  "douses  the  glim/'  By  pulling  the 
lantern  up  and  letting  it  drop  back  into  the  bucket,  a  dot  or  dash 
can  be  made  by  timing  the  length  of  lantern's  exposure. 

The  blinker  on  the  left  of  Chart  18  is  operated  electrically 
by  using  a  telegraph  key.  A  miniature  receptacle  can  be  pur- 
chased at  any  electrical  shop.  This  can  be  mounted  on  a  wooden 
block  and  nailed  to  top  of  a  pole  or  in  fact  any  other  suitable 
place.  A  small  2  or  3  candle  power  light  can  be  used  in  the 
receptacle  for  the  light.  (A  3  candle  power  light  is  good  for  a 
distance  of  54  of  a  mile  without  the  use  of  binoculars.)  One 
light  copper  insulated  wire  is  run  from  one  terminal  of  recep- 
tacle to  the  dry  cell  batteries,  which  are  connected  in  series. 
Another  wire  is  run  down  from  the  other  terminal  of  receptacle 
to  the  key  and  then  to  the  batteries. 

Two  dry  cell  batteries  will  be  strong  enough  to  cause  a  3 
candle  power  lamp  to  work  satisfactorily. 


MEMORANDUM 


MEMORANDUM 


MEMORANDUM 


MEMORANDUM 


MEMORANDUM 


MEMORANDUM 


MEMORANDUM 


MEMORANDUM 


WHAT'S  HE 
SENDING? 

Watch  carefully.  Don't 
let  a  flash  get  by  you. 
Can  you  read  the  mes- 
sage? You  can  if  you 
know  SIGNALS.  And 
you' 11  know  SIGNALS 
if  you'  ve  learned  about 
all  kinds  —  from  the 
simple  smoke  and  fire 
signals  that  have  been 
used  for  many  years  to 
the  modern  electric  sig- 
nals of  today  —  with  an 
outfit  of 

GILBERT 
SIGNAL  ENGINEERING 

Boys,  you  want  to  get  in  on  this  great  sport.  It  will  keep  you  and 
the  rest  of  the  fellows  going  every  minute  —  at  camp,  on  hikes, 
outdoors,  everywhere.  The  Gilbert  Signal  Engineering  Outfit 
contains  wires  and  lights  for  an  electric  Ardois  system,  besides 
apparatus  for  other  systems,  and  a  big  book  on  signals  written  by  a 
man  who  was  formerly  in  the  Signal  Division  of  the  U.  S.  Navy. 
The  book  tells  you  about  many  kinds  of  signals,  gives  the  codes, 
etc. ,  shows  how  to  build  apparatus  of  your  own  and  operate  it,  how 
to  recognize  signals  used  by  ships  out  at  sea  and  many  other  impor- 
tant facts.  Your  dealer  should  sell  Gilbert  Toys.  If  he  doesn't, 
write  us,  and  we'll  tell  you  where  you  can  get  them. 

THE  A.  C.  GILBERT  COMPANY 

511  BLATCHLEY  AVE.  NEW  HAVEN,  CONN. 

In  Canada:  The  A.  C.  Gilbert- Menzies  Co.,  Limited,  Toronto,  Ont. 
In  England:  The  A.  C.  Gilbert  Co.,  125  High  Holborn,  London,  W.  C.  1 


In  the  Dark! 

A  knock  on  the  head  with 
a  hatchet  or  a  stab  with  a 
knife  doesn't  sound  pleasant, 
but  you'll  enjoy  apparent 
treatment  of  this  kind  and 
so  will  your  friends  who 
watch  your  shadow  show. 
Make  your  boy  friend  rise 
in  the  air—change  him  into 
a  bird  or  a  cat — create 
freakish  images.  It's  easy! 
And  laugh— your  audience 
sure  will  enjoy  it  because  it's 
new — nothing  like  it.  An 
entertainment  made  for 
boys  who  want  real  fun. 
But  that's  only  a  few  of  the 
many  things  you  can  do  with 

GILBERT 
LIGHT  EXPERIMENTS 

One  of  these  outfits  will  help  you  to  understand  a  great  many  facts  about  light. 
You  can  perform  a  number  of  experiments  which  explain  the  laws  of  light. 
Learn  about  the  movie  machine,  the  telescope  and  other  optical  instruments. 
There's  a  big  book  on  Light  with  each  set,  it's  a  handy  size,  just  right  to  put  in 
your  pocket. 

From  this  book  and  your  set  you'll  get  a  knowledge  of  light  that  will  be  helpful 
to  you  always.  It's  great  fun  too,  the  kind  you  like.  The  outfit  is  complete  with 
prisms,  mirrors  and  all  the  apparatus  you'll  need  to  perform  the  experiments. 

Ask  your  dealer  to  show  you  this  new  Gilbert  toy. 
If  he  hasn't  it  write 

THE  A.  C.  GILBERT  COMPANY 

511  Blatchley  Ave.,  New  Haven,  Conn. 

In  Canada  — The  A.  C.  Gilbert-Menzies  Co.,  Limited,  Toronto,  Ont. 

In  England —The  A.  C.  Gilbert  Co.,   125  High  Holborn,  London,  W.  C.  1 


WHAT  IS 
MAGNETISM? 

Did  it  ever  seem  strange 
to  you  that  a  compass 
always  points  to  the 
North?  Do  you  know 
why  it  does  —  what  it  is 
that  attracts  the  fine 
needle  point  of  the 
compass?  Very  few 
boys  do.  But  they  are 
the  boys  who  have  never 
heard  of  magnetism  and 
do  not  realize  what  a 
tremendous  effect  it  has 
on  our  every- day  life. 

Gilbert 
Magnetic  Fun  and  Facts 

Is  an  outfit  that  you  will  find  intensely  interesting.  It  explains  in  a 
very  easy  way  all  about  the  compass  and  many  other  things  besides. 
It  shows  you  how  to  build  a  simple  magnetic  motor,  a  corking  little 
electric  shocker,  a  magnetic  tight  rope  walker,  magnetic  jack  straws, 
a  magnetic  navy,  and  any  number  of  electrical  tricks  with  which  you 
can  surprise  your  friends.  You'll  like  this  outfit  and  the  big  book 
which  comes  with  it  telling  you  many  things  about  electricity  and 
magnetism  you  never  dreamed  of. 

The  best  toy  dealer  in  your  city  sells  Gilbert  Magnetic  Fun  and  Facts 
as  well  as  all  other  Gilbert  Toys.  If  you  don't  find  just  what  you 
want,  write  us. 

THE  A.  C.  GILBERT  COMPANY 

511  BLATCHLEY  AVE.  NEW  HAVEN,  CONN. 

la  Canada:  The  A.  C.  Gilbert- Menzies  Co.,  Limited,  Toronto 
In  England:  The  A.  C  Gilbert  Co.,  125  High  Holborn,  London,  W.  C.  2 


The  Greatest 
BookforBoys 
in  Years 


BOY  ENGINEERING 


The  Most  Helpful 
Book  for  Boys  Ever 
Published 


Think  of  it!  "Football  Strategy,"  by  Walter 
Camp— "How  to  Pole  Vault,"  by  Former 
World's  Champion,  A.  C  Gilbert— "Flying," 
by    Eddie    Rickenbacker,     and     "  Athletic 
Training,"    by    the    famous    Yale    trainer, 
Johnny  Mack.     Chapters  about   signalling, 
wireless,    wonderful    heat,    sound    and 
light  experiments,  how  to  build  a  real 
weather  bureau  station   of  your  own, 
chemistry  for  boys,  electrical,  hydraulic 
and  pneumatic  engineering  and  surveying, 
practical  carpentry — all  in  one  finelyillus- 
trated  book.    It's  yours  for  a  quarter  and 
worth  dollars  to  you. 

Buy  it  from  your  dealer,  or 

send  us  2Sc  to-day.    You'll 

never  be  sorry 

The  A.C.  Gilbert 
Company 

511  Blatchley  Avenue 
New  Haven    :    Conn. 


YB  23925 


23 


THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


